diff --git a/libc/Android.bp b/libc/Android.bp
index 701a1b0..b0e0d8c 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -787,7 +787,7 @@
 
     // Disable FORTIFY for the compilation of these, so we don't end up having
     // FORTIFY silently call itself.
-    cflags: ["-U_FORTIFY_SOURCE"],
+    cflags: ["-U_FORTIFY_SOURCE", "-D__BIONIC_DECLARE_FORTIFY_HELPERS"],
 
     arch: {
         arm: {
diff --git a/libc/SECCOMP_WHITELIST.TXT b/libc/SECCOMP_WHITELIST.TXT
index 0b9dad3..9e417c4 100644
--- a/libc/SECCOMP_WHITELIST.TXT
+++ b/libc/SECCOMP_WHITELIST.TXT
@@ -63,7 +63,7 @@
 
 # b/34651972
 int	access:access(const char *pathname, int mode)	arm,x86,mips
-int	stat64:stat64(const char *restrict path, struct stat64 *restrict buf)	arm,x86,mips
+int	stat64:stat64(const char*, struct stat64*)	arm,x86,mips
 
 # b/34813887
 int	open:open(const char *path, int oflag, ... ) arm,x86,mips
@@ -88,7 +88,7 @@
 int	unlink:unlink(const char *pathname)	arm,x86,mips
 
 # b/35059702
-int	lstat64:lstat64(const char *restrict path, struct stat64 *restrict buf)	arm,x86,mips
+int	lstat64:lstat64(const char*, struct stat64*)	arm,x86,mips
 
 # b/35217603
 int	fcntl:fcntl(int fd, int cmd, ... /* arg */ )	arm,x86,mips
@@ -126,4 +126,4 @@
 int compat_select:_newselect(int n, unsigned long* inp, unsigned long* outp, unsigned long* exp, struct timeval* timeout) arm,x86,mips
 
 # b/62090571
-int mkdir(const char *pathname, mode_t mode)	arm,x86,mips
\ No newline at end of file
+int mkdir(const char *pathname, mode_t mode)	arm,x86,mips
diff --git a/libc/bionic/fortify.cpp b/libc/bionic/fortify.cpp
index 4a7ff13..eaf5387 100644
--- a/libc/bionic/fortify.cpp
+++ b/libc/bionic/fortify.cpp
@@ -103,8 +103,7 @@
   return fgets(dst, supplied_size, stream);
 }
 
-size_t __fread_chk(void* __restrict buf, size_t size, size_t count,
-                   FILE* __restrict stream, size_t buf_size) {
+size_t __fread_chk(void* buf, size_t size, size_t count, FILE* stream, size_t buf_size) {
   size_t total;
   if (__predict_false(__size_mul_overflow(size, count, &total))) {
     // overflow: trigger the error path in fread
@@ -114,8 +113,7 @@
   return fread(buf, size, count, stream);
 }
 
-size_t __fwrite_chk(const void* __restrict buf, size_t size, size_t count,
-                    FILE* __restrict stream, size_t buf_size) {
+size_t __fwrite_chk(const void* buf, size_t size, size_t count, FILE* stream, size_t buf_size) {
   size_t total;
   if (__predict_false(__size_mul_overflow(size, count, &total))) {
     // overflow: trigger the error path in fwrite
@@ -239,8 +237,7 @@
 }
 
 // Runtime implementation of __builtin____stpncpy_chk (used directly by compiler, not in headers).
-extern "C" char* __stpncpy_chk(char* __restrict dst, const char* __restrict src,
-                               size_t len, size_t dst_len) {
+extern "C" char* __stpncpy_chk(char* dst, const char* src, size_t len, size_t dst_len) {
   __check_buffer_access("stpncpy", "write into", len, dst_len);
   return stpncpy(dst, src, len);
 }
@@ -249,8 +246,7 @@
 // sure we don't read beyond the end of "src". The code for this is
 // based on the original version of stpncpy, but modified to check
 // how much we read from "src" at the end of the copy operation.
-char* __stpncpy_chk2(char* __restrict dst, const char* __restrict src,
-                     size_t n, size_t dst_len, size_t src_len) {
+char* __stpncpy_chk2(char* dst, const char* src, size_t n, size_t dst_len, size_t src_len) {
   __check_buffer_access("stpncpy", "write into", n, dst_len);
   if (n != 0) {
     char* d = dst;
@@ -325,8 +321,7 @@
 }
 
 // Runtime implementation of __builtin____strncat_chk (used directly by compiler, not in headers).
-extern "C" char* __strncat_chk(char* __restrict dst, const char* __restrict src,
-                               size_t len, size_t dst_buf_size) {
+extern "C" char* __strncat_chk(char* dst, const char* src, size_t len, size_t dst_buf_size) {
   if (len == 0) {
     return dst;
   }
@@ -353,8 +348,7 @@
 }
 
 // Runtime implementation of __builtin____strncpy_chk (used directly by compiler, not in headers).
-extern "C" char* __strncpy_chk(char* __restrict dst, const char* __restrict src,
-                               size_t len, size_t dst_len) {
+extern "C" char* __strncpy_chk(char* dst, const char* src, size_t len, size_t dst_len) {
   __check_buffer_access("strncpy", "write into", len, dst_len);
   return strncpy(dst, src, len);
 }
@@ -363,8 +357,7 @@
 // sure we don't read beyond the end of "src". The code for this is
 // based on the original version of strncpy, but modified to check
 // how much we read from "src" at the end of the copy operation.
-char* __strncpy_chk2(char* __restrict dst, const char* __restrict src,
-                                size_t n, size_t dst_len, size_t src_len) {
+char* __strncpy_chk2(char* dst, const char* src, size_t n, size_t dst_len, size_t src_len) {
   __check_buffer_access("strncpy", "write into", n, dst_len);
   if (n != 0) {
     char* d = dst;
@@ -459,8 +452,7 @@
 
 #if !defined(NO___STRCAT_CHK)
 // Runtime implementation of __builtin____strcat_chk (used directly by compiler, not in headers).
-extern "C" char* __strcat_chk(char* __restrict dst, const char* __restrict src,
-                              size_t dst_buf_size) {
+extern "C" char* __strcat_chk(char* dst, const char* src, size_t dst_buf_size) {
   char* save = dst;
   size_t dst_len = __strlen_chk(dst, dst_buf_size);
 
diff --git a/libc/include/bits/fortify/fcntl.h b/libc/include/bits/fortify/fcntl.h
new file mode 100644
index 0000000..1d3d7bc
--- /dev/null
+++ b/libc/include/bits/fortify/fcntl.h
@@ -0,0 +1,145 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _FCNTL_H
+#error "Never include this file directly; instead, include <fcntl.h>"
+#endif
+
+int __open_2(const char*, int) __INTRODUCED_IN(17);
+int __openat_2(int, const char*, int) __INTRODUCED_IN(17);
+/*
+ * These are the easiest way to call the real open even in clang FORTIFY.
+ */
+int __open_real(const char*, int, ...) __RENAME(open);
+int __openat_real(int, const char*, int, ...) __RENAME(openat);
+
+#if defined(__BIONIC_FORTIFY)
+#define __open_too_many_args_error "too many arguments"
+#define __open_too_few_args_error "called with O_CREAT, but missing mode"
+#if defined(__clang__)
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int open(const char* pathname, int flags, mode_t modes, ...) __overloadable
+        __errorattr(__open_too_many_args_error);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int open(const char* pathname, int flags) __overloadable
+        __enable_if(flags & O_CREAT, __open_too_few_args_error)
+        __errorattr(__open_too_few_args_error);
+
+/*
+ * pass_object_size serves two purposes here, neither of which involve __bos: it
+ * disqualifies this function from having its address taken (so &open works),
+ * and it makes overload resolution prefer open(const char *, int) over
+ * open(const char *, int, ...).
+ */
+__BIONIC_FORTIFY_INLINE
+int open(const char* const __pass_object_size pathname,
+         int flags) __overloadable {
+    return __open_2(pathname, flags);
+}
+
+__BIONIC_FORTIFY_INLINE
+int open(const char* const __pass_object_size pathname, int flags, mode_t modes)
+        __overloadable {
+    return __open_real(pathname, flags, modes);
+}
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int openat(int dirfd, const char* pathname, int flags) __overloadable
+        __enable_if(flags & O_CREAT, __open_too_few_args_error)
+        __errorattr(__open_too_few_args_error);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int openat(int dirfd, const char* pathname, int flags, mode_t modes, ...)
+        __overloadable
+        __errorattr(__open_too_many_args_error);
+
+__BIONIC_FORTIFY_INLINE
+int openat(int dirfd, const char* const __pass_object_size pathname,
+           int flags) __overloadable {
+    return __openat_2(dirfd, pathname, flags);
+}
+
+__BIONIC_FORTIFY_INLINE
+int openat(int dirfd, const char* const __pass_object_size pathname, int flags,
+           mode_t modes) __overloadable {
+    return __openat_real(dirfd, pathname, flags, modes);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#else /* defined(__clang__) */
+__errordecl(__creat_missing_mode, __open_too_few_args_error);
+__errordecl(__creat_too_many_args, __open_too_many_args_error);
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE
+int open(const char* pathname, int flags, ...) {
+    if (__builtin_constant_p(flags)) {
+        if ((flags & O_CREAT) && __builtin_va_arg_pack_len() == 0) {
+            __creat_missing_mode();  /* Compile time error. */
+        }
+    }
+
+    if (__builtin_va_arg_pack_len() > 1) {
+        __creat_too_many_args();  /* Compile time error. */
+    }
+
+    if ((__builtin_va_arg_pack_len() == 0) && !__builtin_constant_p(flags)) {
+        return __open_2(pathname, flags);
+    }
+
+    return __open_real(pathname, flags, __builtin_va_arg_pack());
+}
+
+__BIONIC_FORTIFY_INLINE
+int openat(int dirfd, const char* pathname, int flags, ...) {
+    if (__builtin_constant_p(flags)) {
+        if ((flags & O_CREAT) && __builtin_va_arg_pack_len() == 0) {
+            __creat_missing_mode();  /* Compile time error. */
+        }
+    }
+
+    if (__builtin_va_arg_pack_len() > 1) {
+        __creat_too_many_args();  /* Compile time error. */
+    }
+
+    if ((__builtin_va_arg_pack_len() == 0) && !__builtin_constant_p(flags)) {
+        return __openat_2(dirfd, pathname, flags);
+    }
+
+    return __openat_real(dirfd, pathname, flags, __builtin_va_arg_pack());
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#endif /* defined(__clang__) */
+
+#undef __open_too_many_args_error
+#undef __open_too_few_args_error
+#endif /* defined(__BIONIC_FORTIFY) */
diff --git a/libc/include/bits/fortify/poll.h b/libc/include/bits/fortify/poll.h
new file mode 100644
index 0000000..e9b52c8
--- /dev/null
+++ b/libc/include/bits/fortify/poll.h
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _POLL_H_
+#error "Never include this file directly; instead, include <poll.h>"
+#endif
+
+int __poll_chk(struct pollfd*, nfds_t, int, size_t) __INTRODUCED_IN(23);
+int __ppoll_chk(struct pollfd*, nfds_t, const struct timespec*, const sigset_t*, size_t)
+  __INTRODUCED_IN(23);
+
+#if defined(__BIONIC_FORTIFY)
+#if __ANDROID_API__ >= __ANDROID_API_M__
+#if defined(__clang__)
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int poll(struct pollfd* fds, nfds_t fd_count, int timeout) __overloadable
+        __enable_if(__bos(fds) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                    __bos(fds) < sizeof(*fds) * fd_count,
+                    "selected when there aren't fd_count fds")
+        __errorattr("too many fds specified");
+
+__BIONIC_FORTIFY_INLINE
+int poll(struct pollfd* const fds __pass_object_size, nfds_t fd_count,
+        int timeout) __overloadable {
+  size_t bos_fds = __bos(fds);
+
+  if (bos_fds == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+      return __call_bypassing_fortify(poll)(fds, fd_count, timeout);
+  }
+
+  return __poll_chk(fds, fd_count, timeout, bos_fds);
+}
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int ppoll(struct pollfd* fds, nfds_t fd_count, const struct timespec* timeout,
+          const sigset_t* mask)  __overloadable
+        __enable_if(__bos(fds) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                    __bos(fds) < sizeof(*fds) * fd_count,
+                    "selected when there aren't fd_count fds")
+        __errorattr("too many fds specified");
+
+__BIONIC_FORTIFY_INLINE
+int ppoll(struct pollfd* const fds __pass_object_size, nfds_t fd_count,
+          const struct timespec* timeout, const sigset_t* mask) __overloadable {
+  size_t bos_fds = __bos(fds);
+
+  if (bos_fds == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+      return __call_bypassing_fortify(ppoll)(fds, fd_count, timeout, mask);
+  }
+
+  return __ppoll_chk(fds, fd_count, timeout, mask, bos_fds);
+}
+#else /* defined(__clang__) */
+int __poll_real(struct pollfd*, nfds_t, int) __RENAME(poll);
+__errordecl(__poll_too_small_error, "poll: pollfd array smaller than fd count");
+
+int __ppoll_real(struct pollfd*, nfds_t, const struct timespec*, const sigset_t*) __RENAME(ppoll)
+  __INTRODUCED_IN(21);
+__errordecl(__ppoll_too_small_error, "ppoll: pollfd array smaller than fd count");
+
+__BIONIC_FORTIFY_INLINE
+int poll(struct pollfd* fds, nfds_t fd_count, int timeout) {
+  if (__bos(fds) != __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+    if (!__builtin_constant_p(fd_count)) {
+      return __poll_chk(fds, fd_count, timeout, __bos(fds));
+    } else if (__bos(fds) / sizeof(*fds) < fd_count) {
+      __poll_too_small_error();
+    }
+  }
+  return __poll_real(fds, fd_count, timeout);
+}
+
+__BIONIC_FORTIFY_INLINE
+int ppoll(struct pollfd* fds, nfds_t fd_count, const struct timespec* timeout,
+          const sigset_t* mask) {
+  if (__bos(fds) != __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+    if (!__builtin_constant_p(fd_count)) {
+      return __ppoll_chk(fds, fd_count, timeout, mask, __bos(fds));
+    } else if (__bos(fds) / sizeof(*fds) < fd_count) {
+      __ppoll_too_small_error();
+    }
+  }
+  return __ppoll_real(fds, fd_count, timeout, mask);
+}
+
+#endif /* defined(__clang__) */
+#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
+#endif /* defined(__BIONIC_FORTIFY) */
diff --git a/libc/include/bits/fortify/socket.h b/libc/include/bits/fortify/socket.h
new file mode 100644
index 0000000..c9e9436
--- /dev/null
+++ b/libc/include/bits/fortify/socket.h
@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _SYS_SOCKET_H_
+#error "Never include this file directly; instead, include <sys/socket.h>"
+#endif
+
+extern ssize_t __sendto_chk(int, const void*, size_t, size_t, int, const struct sockaddr*,
+        socklen_t) __INTRODUCED_IN(26);
+ssize_t __recvfrom_chk(int, void*, size_t, size_t, int, struct sockaddr*,
+        socklen_t*) __INTRODUCED_IN(21);
+
+#if defined(__BIONIC_FORTIFY)
+
+#define __recvfrom_bad_size "recvfrom called with size bigger than buffer"
+#define __sendto_bad_size "sendto called with size bigger than buffer"
+#if defined(__clang__)
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t recvfrom(int fd, void* const buf __pass_object_size0, size_t len,
+                 int flags, struct sockaddr* src_addr, socklen_t* addr_len)
+        __overloadable
+        __enable_if(__bos(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                    __bos(buf) < len, "selected when the buffer is too small")
+        __errorattr(__recvfrom_bad_size);
+
+__BIONIC_FORTIFY_INLINE
+ssize_t recvfrom(int fd, void* const buf __pass_object_size0, size_t len,
+                 int flags, struct sockaddr* src_addr, socklen_t* addr_len)
+      __overloadable {
+  size_t bos = __bos0(buf);
+
+  if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+    return __call_bypassing_fortify(recvfrom)(fd, buf, len, flags, src_addr,
+              addr_len);
+  }
+
+  return __recvfrom_chk(fd, buf, len, bos, flags, src_addr, addr_len);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_N_MR1__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t sendto(int fd, const void* buf, size_t len, int flags,
+               const struct sockaddr* dest_addr, socklen_t addr_len)
+        __overloadable
+        __enable_if(__bos0(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                    __bos0(buf) < len, "selected when the buffer is too small")
+        __errorattr(__sendto_bad_size);
+
+__BIONIC_FORTIFY_INLINE
+ssize_t sendto(int fd, const void* const buf __pass_object_size0, size_t len,
+               int flags, const struct sockaddr* dest_addr, socklen_t addr_len)
+      __overloadable {
+  size_t bos = __bos0(buf);
+
+  if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+    return __call_bypassing_fortify(sendto)(fd, buf, len, flags, dest_addr,
+              addr_len);
+  }
+
+  return __sendto_chk(fd, buf, len, bos, flags, dest_addr, addr_len);
+}
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t send(int socket, const void* buf, size_t len, int flags)
+        __overloadable
+        __enable_if(__bos0(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                    __bos0(buf) < len, "selected when the buffer is too small")
+        __errorattr("send called with size bigger than buffer");
+#endif /* __ANDROID_API__ >= __ANDROID_API_N_MR1__ */
+
+#else /* defined(__clang__) */
+ssize_t __recvfrom_real(int, void*, size_t, int, struct sockaddr*, socklen_t*) __RENAME(recvfrom);
+__errordecl(__recvfrom_error, __recvfrom_bad_size);
+
+extern ssize_t __sendto_real(int, const void*, size_t, int, const struct sockaddr*, socklen_t)
+        __RENAME(sendto);
+__errordecl(__sendto_error, __sendto_bad_size);
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_FORTIFY_INLINE
+ssize_t recvfrom(int fd, void* buf, size_t len, int flags,
+                 struct sockaddr* src_addr, socklen_t* addr_len) {
+  size_t bos = __bos0(buf);
+
+  if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+    return __recvfrom_real(fd, buf, len, flags, src_addr, addr_len);
+  }
+
+  if (__builtin_constant_p(len) && (len <= bos)) {
+    return __recvfrom_real(fd, buf, len, flags, src_addr, addr_len);
+  }
+
+  if (__builtin_constant_p(len) && (len > bos)) {
+    __recvfrom_error();
+  }
+
+  return __recvfrom_chk(fd, buf, len, bos, flags, src_addr, addr_len);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_N_MR1__
+__BIONIC_FORTIFY_INLINE
+ssize_t sendto(int fd, const void* buf, size_t len, int flags,
+               const struct sockaddr* dest_addr, socklen_t addr_len) {
+  size_t bos = __bos0(buf);
+
+  if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+    return __sendto_real(fd, buf, len, flags, dest_addr, addr_len);
+  }
+
+  if (__builtin_constant_p(len) && (len <= bos)) {
+    return __sendto_real(fd, buf, len, flags, dest_addr, addr_len);
+  }
+
+  if (__builtin_constant_p(len) && (len > bos)) {
+    __sendto_error();
+  }
+
+  return __sendto_chk(fd, buf, len, bos, flags, dest_addr, addr_len);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N_MR1__ */
+
+#endif /* defined(__clang__) */
+#undef __recvfrom_bad_size
+#undef __sendto_bad_size
+
+__BIONIC_FORTIFY_INLINE
+ssize_t recv(int socket, void* const buf __pass_object_size0, size_t len,
+             int flags) __overloadable {
+  return recvfrom(socket, buf, len, flags, NULL, 0);
+}
+
+__BIONIC_FORTIFY_INLINE
+ssize_t send(int socket, const void* const buf __pass_object_size0, size_t len, int flags)
+        __overloadable {
+  return sendto(socket, buf, len, flags, NULL, 0);
+}
+
+#endif /* __BIONIC_FORTIFY */
diff --git a/libc/include/bits/fortify/stat.h b/libc/include/bits/fortify/stat.h
new file mode 100644
index 0000000..d119e2c
--- /dev/null
+++ b/libc/include/bits/fortify/stat.h
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _SYS_STAT_H_
+#error "Never include this file directly; instead, include <sys/stat.h>"
+#endif
+
+mode_t __umask_chk(mode_t) __INTRODUCED_IN(18);
+
+#if defined(__BIONIC_FORTIFY)
+#define __umask_invalid_mode_str "umask called with invalid mode"
+
+#if defined(__clang__)
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR2__
+/*
+ * Abuse enable_if to make these be seen as overloads of umask, rather than
+ * definitions.
+ */
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+mode_t umask(mode_t mode) __overloadable
+        __enable_if(1, "")
+        __enable_if(mode & ~0777, __umask_invalid_mode_str)
+        __errorattr(__umask_invalid_mode_str);
+
+__BIONIC_FORTIFY_INLINE
+mode_t umask(mode_t mode) __enable_if(1, "") __overloadable {
+  return __umask_chk(mode);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
+
+#else /* defined(__clang__) */
+__errordecl(__umask_invalid_mode, __umask_invalid_mode_str);
+extern mode_t __umask_real(mode_t) __RENAME(umask);
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR2__
+__BIONIC_FORTIFY_INLINE
+mode_t umask(mode_t mode) {
+  if (__builtin_constant_p(mode)) {
+    if ((mode & 0777) != mode) {
+      __umask_invalid_mode();
+    }
+    return __umask_real(mode);
+  }
+  return __umask_chk(mode);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
+
+#endif /* defined(__clang__) */
+#undef __umask_invalid_mode_str
+
+#endif /* defined(__BIONIC_FORTIFY) */
diff --git a/libc/include/bits/fortify/stdio.h b/libc/include/bits/fortify/stdio.h
new file mode 100644
index 0000000..22dc217
--- /dev/null
+++ b/libc/include/bits/fortify/stdio.h
@@ -0,0 +1,282 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _STDIO_H_
+#error "Never include this file directly; instead, include <stdio.h>"
+#endif
+
+char* __fgets_chk(char*, int, FILE*, size_t) __INTRODUCED_IN(17);
+size_t __fread_chk(void*, size_t, size_t, FILE*, size_t) __INTRODUCED_IN(24);
+size_t __fwrite_chk(const void*, size_t, size_t, FILE*, size_t) __INTRODUCED_IN(24);
+
+#if defined(__BIONIC_FORTIFY) && !defined(__BIONIC_NO_STDIO_FORTIFY)
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE __printflike(3, 0)
+int vsnprintf(char *const __pass_object_size dest, size_t size,
+              const char *_Nonnull format, __va_list ap) __overloadable {
+    return __builtin___vsnprintf_chk(dest, size, 0, __bos(dest), format, ap);
+}
+
+__BIONIC_FORTIFY_INLINE __printflike(2, 0)
+int vsprintf(char *const __pass_object_size dest, const char *_Nonnull format,
+             __va_list ap) __overloadable {
+    return __builtin___vsprintf_chk(dest, 0, __bos(dest), format, ap);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#if defined(__clang__)
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+/*
+ * Simple case: `format` can't have format specifiers, so we can just compare
+ * its length to the length of `dest`
+ */
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int snprintf(char* dest, size_t size, const char* format)
+    __overloadable
+    __enable_if(__bos(dest) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                __bos(dest) < __builtin_strlen(format),
+                "format string will always overflow destination buffer")
+    __errorattr("format string will always overflow destination buffer");
+
+__BIONIC_FORTIFY_INLINE
+__printflike(3, 4)
+int snprintf(char* const __pass_object_size dest,
+             size_t size, const char* format, ...) __overloadable {
+    va_list va;
+    va_start(va, format);
+    int result = __builtin___vsnprintf_chk(dest, size, 0, __bos(dest), format, va);
+    va_end(va);
+    return result;
+}
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+int sprintf(char* dest, const char* format) __overloadable
+    __enable_if(__bos(dest) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                __bos(dest) < __builtin_strlen(format),
+                "format string will always overflow destination buffer")
+    __errorattr("format string will always overflow destination buffer");
+
+__BIONIC_FORTIFY_INLINE
+__printflike(2, 3)
+int sprintf(char* const __pass_object_size dest, const char* format, ...) __overloadable {
+    va_list va;
+    va_start(va, format);
+    int result = __builtin___vsprintf_chk(dest, 0, __bos(dest), format, va);
+    va_end(va);
+    return result;
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_FORTIFY_INLINE
+size_t fread(void* buf, size_t size, size_t count,
+             FILE* stream) __overloadable
+        __enable_if(__unsafe_check_mul_overflow(size, count), "size * count overflows")
+        __errorattr("size * count overflows");
+
+__BIONIC_FORTIFY_INLINE
+size_t fread(void* buf, size_t size, size_t count, FILE* stream) __overloadable
+    __enable_if(!__unsafe_check_mul_overflow(size, count), "no overflow")
+    __enable_if(__bos(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                size * count > __bos(buf), "size * count is too large")
+    __errorattr("size * count is too large");
+
+__BIONIC_FORTIFY_INLINE
+size_t fread(void* const __pass_object_size0 buf, size_t size,
+             size_t count, FILE* stream) __overloadable {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(fread)(buf, size, count, stream);
+    }
+
+    return __fread_chk(buf, size, count, stream, bos);
+}
+
+size_t fwrite(const void* buf, size_t size, size_t count, FILE* stream) __overloadable
+    __enable_if(__unsafe_check_mul_overflow(size, count),
+                "size * count overflows")
+    __errorattr("size * count overflows");
+
+size_t fwrite(const void* buf, size_t size, size_t count, FILE* stream) __overloadable
+    __enable_if(!__unsafe_check_mul_overflow(size, count), "no overflow")
+    __enable_if(__bos(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                size * count > __bos(buf), "size * count is too large")
+    __errorattr("size * count is too large");
+
+__BIONIC_FORTIFY_INLINE
+size_t fwrite(const void* const __pass_object_size0 buf, size_t size, size_t count, FILE* stream)
+        __overloadable {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(fwrite)(buf, size, count, stream);
+    }
+
+    return __fwrite_chk(buf, size, count, stream, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+char *fgets(char* dest, int size, FILE* stream) __overloadable
+    __enable_if(size < 0, "size is negative")
+    __errorattr("size is negative");
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+char *fgets(char* dest, int size, FILE* stream) __overloadable
+    __enable_if(size >= 0 && size > __bos(dest),
+                "size is larger than the destination buffer")
+    __errorattr("size is larger than the destination buffer");
+
+__BIONIC_FORTIFY_INLINE
+char *fgets(char* const __pass_object_size dest, int size, FILE* stream) __overloadable {
+    size_t bos = __bos(dest);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(fgets)(dest, size, stream);
+    }
+
+    return __fgets_chk(dest, size, stream, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#else /* defined(__clang__) */
+
+size_t __fread_real(void*, size_t, size_t, FILE*) __RENAME(fread);
+__errordecl(__fread_too_big_error, "fread called with size * count bigger than buffer");
+__errordecl(__fread_overflow, "fread called with overflowing size * count");
+
+char* __fgets_real(char*, int, FILE*) __RENAME(fgets);
+__errordecl(__fgets_too_big_error, "fgets called with size bigger than buffer");
+__errordecl(__fgets_too_small_error, "fgets called with size less than zero");
+
+size_t __fwrite_real(const void*, size_t, size_t, FILE*) __RENAME(fwrite);
+__errordecl(__fwrite_too_big_error, "fwrite called with size * count bigger than buffer");
+__errordecl(__fwrite_overflow, "fwrite called with overflowing size * count");
+
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE __printflike(3, 4)
+int snprintf(char* dest, size_t size, const char* _Nonnull format, ...) {
+    return __builtin___snprintf_chk(dest, size, 0, __bos(dest), format,
+                                    __builtin_va_arg_pack());
+}
+
+__BIONIC_FORTIFY_INLINE __printflike(2, 3)
+int sprintf(char* dest, const char* _Nonnull format, ...) {
+    return __builtin___sprintf_chk(dest, 0, __bos(dest), format,
+                                   __builtin_va_arg_pack());
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_FORTIFY_INLINE
+size_t fread(void* buf, size_t size, size_t count, FILE* stream) {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __fread_real(buf, size, count, stream);
+    }
+
+    if (__builtin_constant_p(size) && __builtin_constant_p(count)) {
+        size_t total;
+        if (__size_mul_overflow(size, count, &total)) {
+            __fread_overflow();
+        }
+
+        if (total > bos) {
+            __fread_too_big_error();
+        }
+
+        return __fread_real(buf, size, count, stream);
+    }
+
+    return __fread_chk(buf, size, count, stream, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+size_t fwrite(const void* buf, size_t size, size_t count, FILE* stream) {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __fwrite_real(buf, size, count, stream);
+    }
+
+    if (__builtin_constant_p(size) && __builtin_constant_p(count)) {
+        size_t total;
+        if (__size_mul_overflow(size, count, &total)) {
+            __fwrite_overflow();
+        }
+
+        if (total > bos) {
+            __fwrite_too_big_error();
+        }
+
+        return __fwrite_real(buf, size, count, stream);
+    }
+
+    return __fwrite_chk(buf, size, count, stream, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE
+char *fgets(char* dest, int size, FILE* stream) {
+    size_t bos = __bos(dest);
+
+    // Compiler can prove, at compile time, that the passed in size
+    // is always negative. Force a compiler error.
+    if (__builtin_constant_p(size) && (size < 0)) {
+        __fgets_too_small_error();
+    }
+
+    // Compiler doesn't know destination size. Don't call __fgets_chk
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __fgets_real(dest, size, stream);
+    }
+
+    // Compiler can prove, at compile time, that the passed in size
+    // is always <= the actual object size. Don't call __fgets_chk
+    if (__builtin_constant_p(size) && (size <= (int) bos)) {
+        return __fgets_real(dest, size, stream);
+    }
+
+    // Compiler can prove, at compile time, that the passed in size
+    // is always > the actual object size. Force a compiler error.
+    if (__builtin_constant_p(size) && (size > (int) bos)) {
+        __fgets_too_big_error();
+    }
+
+    return __fgets_chk(dest, size, stream, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#endif /* defined(__clang__) */
+#endif /* defined(__BIONIC_FORTIFY) */
diff --git a/libc/include/bits/fortify/stdlib.h b/libc/include/bits/fortify/stdlib.h
new file mode 100644
index 0000000..bda1d45
--- /dev/null
+++ b/libc/include/bits/fortify/stdlib.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _STDLIB_H
+#error "Never include this file directly; instead, include <stdlib.h>"
+#endif
+
+#if defined(__BIONIC_FORTIFY)
+#define __realpath_buf_too_small_str \
+    "realpath output parameter must be NULL or a >= PATH_MAX bytes buffer"
+
+/* PATH_MAX is unavailable without polluting the namespace, but it's always 4096 on Linux */
+#define __PATH_MAX 4096
+
+#if defined(__clang__)
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+char* realpath(const char* path, char* resolved) __overloadable
+    __enable_if(__bos(resolved) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
+                __bos(resolved) < __PATH_MAX, __realpath_buf_too_small_str)
+    __errorattr(__realpath_buf_too_small_str);
+
+/* No need for a FORTIFY version; the only things we can catch are at
+ * compile-time.
+ */
+
+#else /* defined(__clang__) */
+
+char* __realpath_real(const char*, char*) __RENAME(realpath);
+__errordecl(__realpath_size_error, __realpath_buf_too_small_str);
+
+__BIONIC_FORTIFY_INLINE
+char* realpath(const char* path, char* resolved) {
+    size_t bos = __bos(resolved);
+
+    if (bos != __BIONIC_FORTIFY_UNKNOWN_SIZE && bos < __PATH_MAX) {
+        __realpath_size_error();
+    }
+
+    return __realpath_real(path, resolved);
+}
+
+#endif /* defined(__clang__) */
+
+#undef __PATH_MAX
+#undef __realpath_buf_too_small_str
+#endif /* defined(__BIONIC_FORTIFY) */
diff --git a/libc/include/bits/fortify/string.h b/libc/include/bits/fortify/string.h
new file mode 100644
index 0000000..2fe48d4
--- /dev/null
+++ b/libc/include/bits/fortify/string.h
@@ -0,0 +1,481 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _STRING_H
+#error "Never include this file directly; instead, include <string.h>"
+#endif
+
+void* __memchr_chk(const void* _Nonnull, int, size_t, size_t) __INTRODUCED_IN(23);
+void* __memrchr_chk(const void* _Nonnull, int, size_t, size_t) __INTRODUCED_IN(23);
+char* __stpncpy_chk2(char* _Nonnull, const char* _Nonnull, size_t, size_t, size_t)
+  __INTRODUCED_IN(21);
+char* __strncpy_chk2(char* _Nonnull, const char* _Nonnull, size_t, size_t, size_t)
+  __INTRODUCED_IN(21);
+size_t __strlcpy_chk(char* _Nonnull, const char* _Nonnull, size_t, size_t) __INTRODUCED_IN(17);
+size_t __strlcat_chk(char* _Nonnull, const char* _Nonnull, size_t, size_t) __INTRODUCED_IN(17);
+
+/* Only used with FORTIFY, but some headers that need it undef FORTIFY, so we
+ * have the definition out here.
+ */
+struct __bionic_zero_size_is_okay_t {};
+
+#if defined(__BIONIC_FORTIFY)
+// These can share their implementation between gcc and clang with minimal
+// trickery...
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE
+void* memcpy(void* _Nonnull const dst __pass_object_size0, const void* _Nonnull  src, size_t copy_amount)
+        __overloadable {
+    return __builtin___memcpy_chk(dst, src, copy_amount, __bos0(dst));
+}
+
+__BIONIC_FORTIFY_INLINE
+void* memmove(void* const _Nonnull dst __pass_object_size0, const void* _Nonnull src, size_t len)
+        __overloadable {
+    return __builtin___memmove_chk(dst, src, len, __bos0(dst));
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_L__
+__BIONIC_FORTIFY_INLINE
+char* stpcpy(char* _Nonnull const dst __pass_object_size, const char* _Nonnull src)
+        __overloadable {
+    return __builtin___stpcpy_chk(dst, src, __bos(dst));
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE
+char* strcpy(char* _Nonnull const dst __pass_object_size, const char* _Nonnull src)
+        __overloadable {
+    return __builtin___strcpy_chk(dst, src, __bos(dst));
+}
+
+__BIONIC_FORTIFY_INLINE
+char* strcat(char* _Nonnull const dst __pass_object_size, const char* _Nonnull src)
+        __overloadable {
+    return __builtin___strcat_chk(dst, src, __bos(dst));
+}
+
+__BIONIC_FORTIFY_INLINE
+char* strncat(char* const _Nonnull dst __pass_object_size, const char* _Nonnull src, size_t n)
+        __overloadable {
+    return __builtin___strncat_chk(dst, src, n, __bos(dst));
+}
+
+__BIONIC_FORTIFY_INLINE
+void* memset(void* const _Nonnull s __pass_object_size0, int c, size_t n) __overloadable {
+    return __builtin___memset_chk(s, c, n, __bos0(s));
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+
+#if defined(__clang__)
+
+#define __error_if_overflows_dst(name, dst, n, what) \
+    __enable_if(__bos0(dst) != __BIONIC_FORTIFY_UNKNOWN_SIZE && \
+                __bos0(dst) < (n), "selected when the buffer is too small") \
+    __errorattr(#name " called with " what " bigger than buffer")
+
+/*
+ * N.B. _Nonnull isn't necessary on params, since these functions just emit
+ * errors.
+ */
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+void* memcpy(void* dst, const void* src, size_t copy_amount) __overloadable
+        __error_if_overflows_dst(memcpy, dst, copy_amount, "size");
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+void* memmove(void *dst, const void* src, size_t len) __overloadable
+        __error_if_overflows_dst(memmove, dst, len, "size");
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+void* memset(void* s, int c, size_t n) __overloadable
+        __error_if_overflows_dst(memset, s, n, "size");
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+char* stpcpy(char* dst, const char* src) __overloadable
+        __error_if_overflows_dst(stpcpy, dst, __builtin_strlen(src), "string");
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+char* strcpy(char* dst, const char* src) __overloadable
+        __error_if_overflows_dst(strcpy, dst, __builtin_strlen(src), "string");
+
+#if __ANDROID_API__ >= __ANDROID_API_M__
+__BIONIC_FORTIFY_INLINE
+void* memchr(const void* const _Nonnull s __pass_object_size, int c, size_t n)
+        __overloadable {
+    size_t bos = __bos(s);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin_memchr(s, c, n);
+    }
+
+    return __memchr_chk(s, c, n, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+void* memrchr(const void* const _Nonnull s __pass_object_size, int c, size_t n)
+        __overloadable {
+    size_t bos = __bos(s);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(memrchr)(s, c, n);
+    }
+
+    return __memrchr_chk(s, c, n, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_L__
+__BIONIC_FORTIFY_INLINE
+char* stpncpy(char* const _Nonnull dst __pass_object_size, const char* const _Nonnull src __pass_object_size, size_t n)
+        __overloadable {
+    size_t bos_dst = __bos(dst);
+    size_t bos_src = __bos(src);
+
+    /* Ignore dst size checks; they're handled in strncpy_chk */
+    if (bos_src == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin___stpncpy_chk(dst, src, n, bos_dst);
+    }
+
+    return __stpncpy_chk2(dst, src, n, bos_dst, bos_src);
+}
+
+__BIONIC_FORTIFY_INLINE
+char* strncpy(char* const _Nonnull dst __pass_object_size, const char* const _Nonnull src __pass_object_size, size_t n)
+        __overloadable {
+    size_t bos_dst = __bos(dst);
+    size_t bos_src = __bos(src);
+
+    /* Ignore dst size checks; they're handled in strncpy_chk */
+    if (bos_src == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin___strncpy_chk(dst, src, n, bos_dst);
+    }
+
+    return __strncpy_chk2(dst, src, n, bos_dst, bos_src);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE
+size_t strlcpy(char* const _Nonnull dst __pass_object_size, const char *_Nonnull src, size_t size)
+        __overloadable {
+    size_t bos = __bos(dst);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(strlcpy)(dst, src, size);
+    }
+
+    return __strlcpy_chk(dst, src, size, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+size_t strlcat(char* const _Nonnull dst __pass_object_size, const char* _Nonnull src, size_t size)
+        __overloadable {
+    size_t bos = __bos(dst);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(strlcat)(dst, src, size);
+    }
+
+    return __strlcat_chk(dst, src, size, bos);
+}
+
+/*
+ * If we can evaluate the size of s at compile-time, just call __builtin_strlen
+ * on it directly. This makes it way easier for compilers to fold things like
+ * strlen("Foo") into a constant, as users would expect. -1ULL is chosen simply
+ * because it's large.
+ */
+__BIONIC_FORTIFY_INLINE
+size_t strlen(const char* const _Nonnull s __pass_object_size)
+        __overloadable __enable_if(__builtin_strlen(s) != -1ULL,
+                                   "enabled if s is a known good string.") {
+    return __builtin_strlen(s);
+}
+
+__BIONIC_FORTIFY_INLINE
+size_t strlen(const char* const _Nonnull s __pass_object_size0)
+        __overloadable {
+    size_t bos = __bos0(s);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin_strlen(s);
+    }
+
+    // return __builtin_strlen(s);
+    return __strlen_chk(s, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#if  __ANDROID_API__ >= __ANDROID_API_J_MR2__
+__BIONIC_FORTIFY_INLINE
+char* strchr(const char* const _Nonnull s __pass_object_size, int c)
+        __overloadable {
+    size_t bos = __bos(s);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin_strchr(s, c);
+    }
+
+    return __strchr_chk(s, c, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+char* strrchr(const char* const _Nonnull s __pass_object_size, int c)
+        __overloadable {
+    size_t bos = __bos(s);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin_strrchr(s, c);
+    }
+
+    return __strrchr_chk(s, c, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+/* In *many* cases, memset(foo, sizeof(foo), 0) is a mistake where the user has
+ * flipped the size + value arguments. However, there may be cases (e.g. with
+ * macros) where it's okay for the size to fold to zero. We should warn on this,
+ * but we should also provide a FORTIFY'ed escape hatch.
+ */
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+void* memset(void* _Nonnull s, int c, size_t n, struct __bionic_zero_size_is_okay_t ok)
+        __overloadable
+        __error_if_overflows_dst(memset, s, n, "size");
+
+__BIONIC_FORTIFY_INLINE
+void* memset(void* const _Nonnull s __pass_object_size0, int c, size_t n, struct __bionic_zero_size_is_okay_t ok __attribute__((unused)))
+        __overloadable {
+    return __builtin___memset_chk(s, c, n, __bos0(s));
+}
+
+extern struct __bionic_zero_size_is_okay_t __bionic_zero_size_is_okay;
+/* We verify that `c` is non-zero, because as pointless as memset(foo, 0, 0) is,
+ * flipping size + count will do nothing.
+ */
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+void* memset(void* _Nonnull s, int c, size_t n) __overloadable
+        __enable_if(c && !n, "selected when we'll set zero bytes")
+        __RENAME_CLANG(memset)
+        __warnattr_real("will set 0 bytes; maybe the arguments got flipped? "
+                        "(Add __bionic_zero_size_is_okay as a fourth argument "
+                        "to silence this.)");
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#undef __error_zero_size
+#undef __error_if_overflows_dst
+#else // defined(__clang__)
+extern char* __strncpy_real(char*, const char*, size_t) __RENAME(strncpy);
+extern void* __memrchr_real(const void*, int, size_t) __RENAME(memrchr);
+extern size_t __strlcpy_real(char*, const char*, size_t)
+    __RENAME(strlcpy);
+extern size_t __strlcat_real(char*, const char*, size_t)
+    __RENAME(strlcat);
+
+__errordecl(__memchr_buf_size_error, "memchr called with size bigger than buffer");
+__errordecl(__memrchr_buf_size_error, "memrchr called with size bigger than buffer");
+
+#if __ANDROID_API__ >= __ANDROID_API_M__
+__BIONIC_FORTIFY_INLINE
+void* memchr(const void *_Nonnull s __pass_object_size, int c, size_t n) {
+    size_t bos = __bos(s);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin_memchr(s, c, n);
+    }
+
+    if (__builtin_constant_p(n) && (n > bos)) {
+        __memchr_buf_size_error();
+    }
+
+    if (__builtin_constant_p(n) && (n <= bos)) {
+        return __builtin_memchr(s, c, n);
+    }
+
+    return __memchr_chk(s, c, n, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+void* memrchr(const void* s, int c, size_t n) {
+    size_t bos = __bos(s);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __memrchr_real(s, c, n);
+    }
+
+    if (__builtin_constant_p(n) && (n > bos)) {
+        __memrchr_buf_size_error();
+    }
+
+    if (__builtin_constant_p(n) && (n <= bos)) {
+        return __memrchr_real(s, c, n);
+    }
+
+    return __memrchr_chk(s, c, n, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_L__
+__BIONIC_FORTIFY_INLINE
+char* stpncpy(char* _Nonnull dst, const char* _Nonnull src, size_t n) {
+    size_t bos_dst = __bos(dst);
+    size_t bos_src = __bos(src);
+
+    if (bos_src == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin___stpncpy_chk(dst, src, n, bos_dst);
+    }
+
+    if (__builtin_constant_p(n) && (n <= bos_src)) {
+        return __builtin___stpncpy_chk(dst, src, n, bos_dst);
+    }
+
+    size_t slen = __builtin_strlen(src);
+    if (__builtin_constant_p(slen)) {
+        return __builtin___stpncpy_chk(dst, src, n, bos_dst);
+    }
+
+    return __stpncpy_chk2(dst, src, n, bos_dst, bos_src);
+}
+
+__BIONIC_FORTIFY_INLINE
+char* strncpy(char* _Nonnull dst, const char* _Nonnull src, size_t n) {
+    size_t bos_dst = __bos(dst);
+    size_t bos_src = __bos(src);
+
+    if (bos_src == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __strncpy_real(dst, src, n);
+    }
+
+    if (__builtin_constant_p(n) && (n <= bos_src)) {
+        return __builtin___strncpy_chk(dst, src, n, bos_dst);
+    }
+
+    size_t slen = __builtin_strlen(src);
+    if (__builtin_constant_p(slen)) {
+        return __builtin___strncpy_chk(dst, src, n, bos_dst);
+    }
+
+    return __strncpy_chk2(dst, src, n, bos_dst, bos_src);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
+__BIONIC_FORTIFY_INLINE
+size_t strlcpy(char* _Nonnull dst __pass_object_size, const char* _Nonnull src, size_t size) {
+    size_t bos = __bos(dst);
+
+    // Compiler doesn't know destination size. Don't call __strlcpy_chk
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __strlcpy_real(dst, src, size);
+    }
+
+    // Compiler can prove, at compile time, that the passed in size
+    // is always <= the actual object size. Don't call __strlcpy_chk
+    if (__builtin_constant_p(size) && (size <= bos)) {
+        return __strlcpy_real(dst, src, size);
+    }
+
+    return __strlcpy_chk(dst, src, size, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+size_t strlcat(char* _Nonnull dst, const char* _Nonnull src, size_t size) {
+    size_t bos = __bos(dst);
+
+    // Compiler doesn't know destination size. Don't call __strlcat_chk
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __strlcat_real(dst, src, size);
+    }
+
+    // Compiler can prove, at compile time, that the passed in size
+    // is always <= the actual object size. Don't call __strlcat_chk
+    if (__builtin_constant_p(size) && (size <= bos)) {
+        return __strlcat_real(dst, src, size);
+    }
+
+    return __strlcat_chk(dst, src, size, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+size_t strlen(const char* _Nonnull s) __overloadable {
+    size_t bos = __bos(s);
+
+    // Compiler doesn't know destination size. Don't call __strlen_chk
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin_strlen(s);
+    }
+
+    size_t slen = __builtin_strlen(s);
+    if (__builtin_constant_p(slen)) {
+        return slen;
+    }
+
+    return __strlen_chk(s, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
+
+#if  __ANDROID_API__ >= __ANDROID_API_J_MR2__
+__BIONIC_FORTIFY_INLINE
+char* strchr(const char* _Nonnull s, int c) {
+    size_t bos = __bos(s);
+
+    // Compiler doesn't know destination size. Don't call __strchr_chk
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin_strchr(s, c);
+    }
+
+    size_t slen = __builtin_strlen(s);
+    if (__builtin_constant_p(slen) && (slen < bos)) {
+        return __builtin_strchr(s, c);
+    }
+
+    return __strchr_chk(s, c, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+char* strrchr(const char* _Nonnull s, int c) {
+    size_t bos = __bos(s);
+
+    // Compiler doesn't know destination size. Don't call __strrchr_chk
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __builtin_strrchr(s, c);
+    }
+
+    size_t slen = __builtin_strlen(s);
+    if (__builtin_constant_p(slen) && (slen < bos)) {
+        return __builtin_strrchr(s, c);
+    }
+
+    return __strrchr_chk(s, c, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
+#endif /* defined(__clang__) */
+#endif /* defined(__BIONIC_FORTIFY) */
diff --git a/libc/include/bits/fortify/unistd.h b/libc/include/bits/fortify/unistd.h
new file mode 100644
index 0000000..5df67b4
--- /dev/null
+++ b/libc/include/bits/fortify/unistd.h
@@ -0,0 +1,525 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#ifndef _UNISTD_H_
+#error "Never include this file directly; instead, include <unistd.h>"
+#endif
+
+char* __getcwd_chk(char*, size_t, size_t) __INTRODUCED_IN(24);
+
+ssize_t __pread_chk(int, void*, size_t, off_t, size_t) __INTRODUCED_IN(23);
+ssize_t __pread_real(int, void*, size_t, off_t) __RENAME(pread);
+
+ssize_t __pread64_chk(int, void*, size_t, off64_t, size_t) __INTRODUCED_IN(23);
+ssize_t __pread64_real(int, void*, size_t, off64_t) __RENAME(pread64) __INTRODUCED_IN(12);
+
+ssize_t __pwrite_chk(int, const void*, size_t, off_t, size_t) __INTRODUCED_IN(24);
+ssize_t __pwrite_real(int, const void*, size_t, off_t) __RENAME(pwrite);
+
+ssize_t __pwrite64_chk(int, const void*, size_t, off64_t, size_t) __INTRODUCED_IN(24);
+ssize_t __pwrite64_real(int, const void*, size_t, off64_t) __RENAME(pwrite64)
+  __INTRODUCED_IN(12);
+
+ssize_t __read_chk(int, void*, size_t, size_t) __INTRODUCED_IN(21);
+ssize_t __write_chk(int, const void*, size_t, size_t) __INTRODUCED_IN(24);
+ssize_t __readlink_chk(const char*, char*, size_t, size_t) __INTRODUCED_IN(23);
+ssize_t __readlinkat_chk(int dirfd, const char*, char*, size_t, size_t) __INTRODUCED_IN(23);
+
+#if defined(__BIONIC_FORTIFY)
+
+#if defined(__USE_FILE_OFFSET64)
+#define __PREAD_PREFIX(x) __pread64_ ## x
+#define __PWRITE_PREFIX(x) __pwrite64_ ## x
+#else
+#define __PREAD_PREFIX(x) __pread_ ## x
+#define __PWRITE_PREFIX(x) __pwrite_ ## x
+#endif
+
+#if defined(__clang__)
+#define __error_if_overflows_ssizet(what) \
+    __enable_if(what > SSIZE_MAX, #what " must be <= SSIZE_MAX") \
+    __errorattr(#what " must be <= SSIZE_MAX")
+
+#define __enable_if_no_overflow_ssizet(what) \
+    __enable_if((what) <= SSIZE_MAX, "enabled if " #what " <= SSIZE_MAX")
+
+#define __error_if_overflows_objectsize(what, objsize) \
+    __enable_if((objsize) != __BIONIC_FORTIFY_UNKNOWN_SIZE && \
+                    (what) > (objsize), \
+                "'" #what "' bytes overflows the given object") \
+    __errorattr("'" #what "' bytes overflows the given object")
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+char* getcwd(char* buf, size_t size) __overloadable
+        __error_if_overflows_objectsize(size, __bos(buf));
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_FORTIFY_INLINE
+char* getcwd(char* const __pass_object_size buf, size_t size) __overloadable {
+    size_t bos = __bos(buf);
+
+    /*
+     * Clang responds bos==0 if buf==NULL
+     * (https://llvm.org/bugs/show_bug.cgi?id=23277). Given that NULL is a valid
+     * value, we need to handle that.
+     */
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE || buf == NULL) {
+        return __call_bypassing_fortify(getcwd)(buf, size);
+    }
+
+    return __getcwd_chk(buf, size, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_M__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t pread(int fd, void* buf, size_t count, off_t offset) __overloadable
+        __error_if_overflows_ssizet(count);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t pread(int fd, void* buf, size_t count, off_t offset) __overloadable
+        __enable_if_no_overflow_ssizet(count)
+        __error_if_overflows_objectsize(count, __bos0(buf));
+
+__BIONIC_FORTIFY_INLINE
+ssize_t pread(int fd, void* const __pass_object_size0 buf, size_t count,
+              off_t offset) __overloadable {
+    size_t bos = __bos0(buf);
+
+    if (count == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __PREAD_PREFIX(real)(fd, buf, count, offset);
+    }
+
+    return __PREAD_PREFIX(chk)(fd, buf, count, offset, bos);
+}
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t pread64(int fd, void* buf, size_t count, off64_t offset) __overloadable
+        __error_if_overflows_ssizet(count);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t pread64(int fd, void* buf, size_t count, off64_t offset) __overloadable
+        __enable_if_no_overflow_ssizet(count)
+        __error_if_overflows_objectsize(count, __bos0(buf));
+
+__BIONIC_FORTIFY_INLINE
+ssize_t pread64(int fd, void* const __pass_object_size0 buf, size_t count,
+                off64_t offset) __overloadable {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __pread64_real(fd, buf, count, offset);
+    }
+
+    return __pread64_chk(fd, buf, count, offset, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t pwrite(int fd, const void* buf, size_t count, off_t offset)
+        __overloadable
+        __error_if_overflows_ssizet(count);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t pwrite(int fd, const void* buf, size_t count, off_t offset)
+        __overloadable
+        __enable_if_no_overflow_ssizet(count)
+        __error_if_overflows_objectsize(count, __bos0(buf));
+
+__BIONIC_FORTIFY_INLINE
+ssize_t pwrite(int fd, const void* const __pass_object_size0 buf, size_t count,
+               off_t offset) __overloadable {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __PWRITE_PREFIX(real)(fd, buf, count, offset);
+    }
+
+    return __PWRITE_PREFIX(chk)(fd, buf, count, offset, bos);
+}
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t pwrite64(int fd, const void* buf, size_t count, off64_t offset)
+        __overloadable
+        __error_if_overflows_ssizet(count);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t pwrite64(int fd, const void* buf, size_t count, off64_t offset)
+        __overloadable
+        __enable_if_no_overflow_ssizet(count)
+        __error_if_overflows_objectsize(count, __bos0(buf));
+
+__BIONIC_FORTIFY_INLINE
+ssize_t pwrite64(int fd, const void* const __pass_object_size0 buf,
+                 size_t count, off64_t offset) __overloadable {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __pwrite64_real(fd, buf, count, offset);
+    }
+
+    return __pwrite64_chk(fd, buf, count, offset, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_L__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t read(int fd, void* buf, size_t count) __overloadable
+        __error_if_overflows_ssizet(count);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t read(int fd, void* buf, size_t count) __overloadable
+        __enable_if_no_overflow_ssizet(count)
+        __error_if_overflows_objectsize(count, __bos0(buf));
+
+__BIONIC_FORTIFY_INLINE
+ssize_t read(int fd, void* const __pass_object_size0 buf, size_t count)
+        __overloadable {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(read)(fd, buf, count);
+    }
+
+    return __read_chk(fd, buf, count, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t write(int fd, const void* buf, size_t count) __overloadable
+        __error_if_overflows_ssizet(count);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t write(int fd, const void* buf, size_t count) __overloadable
+        __enable_if_no_overflow_ssizet(count)
+        __error_if_overflows_objectsize(count, __bos0(buf));
+
+__BIONIC_FORTIFY_INLINE
+ssize_t write(int fd, const void* const __pass_object_size0 buf, size_t count)
+        __overloadable {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(write)(fd, buf, count);
+    }
+
+    return __write_chk(fd, buf, count, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_M__
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t readlink(const char* path, char* buf, size_t size) __overloadable
+        __error_if_overflows_ssizet(size);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t readlink(const char* path, char* buf, size_t size) __overloadable
+        __enable_if_no_overflow_ssizet(size)
+        __error_if_overflows_objectsize(size, __bos(buf));
+
+__BIONIC_FORTIFY_INLINE
+ssize_t readlink(const char* path, char* const __pass_object_size buf,
+                 size_t size) __overloadable {
+    size_t bos = __bos(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(readlink)(path, buf, size);
+    }
+
+    return __readlink_chk(path, buf, size, bos);
+}
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t readlinkat(int dirfd, const char* path, char* buf, size_t size)
+        __overloadable
+        __error_if_overflows_ssizet(size);
+
+__BIONIC_ERROR_FUNCTION_VISIBILITY
+ssize_t readlinkat(int dirfd, const char* path, char* buf, size_t size)
+        __overloadable
+        __enable_if_no_overflow_ssizet(size)
+        __error_if_overflows_objectsize(size, __bos(buf));
+
+__BIONIC_FORTIFY_INLINE
+ssize_t readlinkat(int dirfd, const char* path,
+                   char* const __pass_object_size buf, size_t size)
+        __overloadable {
+    size_t bos = __bos(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __call_bypassing_fortify(readlinkat)(dirfd, path, buf, size);
+    }
+
+    return __readlinkat_chk(dirfd, path, buf, size, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
+
+#undef __enable_if_no_overflow_ssizet
+#undef __error_if_overflows_objectsize
+#undef __error_if_overflows_ssizet
+#else /* defined(__clang__) */
+
+char* __getcwd_real(char*, size_t) __RENAME(getcwd);
+ssize_t __read_real(int, void*, size_t) __RENAME(read);
+ssize_t __write_real(int, const void*, size_t) __RENAME(write);
+ssize_t __readlink_real(const char*, char*, size_t) __RENAME(readlink);
+ssize_t __readlinkat_real(int dirfd, const char*, char*, size_t) __RENAME(readlinkat);
+
+__errordecl(__getcwd_dest_size_error, "getcwd called with size bigger than destination");
+__errordecl(__pread_dest_size_error, "pread called with size bigger than destination");
+__errordecl(__pread_count_toobig_error, "pread called with count > SSIZE_MAX");
+__errordecl(__pread64_dest_size_error, "pread64 called with size bigger than destination");
+__errordecl(__pread64_count_toobig_error, "pread64 called with count > SSIZE_MAX");
+__errordecl(__pwrite_dest_size_error, "pwrite called with size bigger than destination");
+__errordecl(__pwrite_count_toobig_error, "pwrite called with count > SSIZE_MAX");
+__errordecl(__pwrite64_dest_size_error, "pwrite64 called with size bigger than destination");
+__errordecl(__pwrite64_count_toobig_error, "pwrite64 called with count > SSIZE_MAX");
+__errordecl(__read_dest_size_error, "read called with size bigger than destination");
+__errordecl(__read_count_toobig_error, "read called with count > SSIZE_MAX");
+__errordecl(__write_dest_size_error, "write called with size bigger than destination");
+__errordecl(__write_count_toobig_error, "write called with count > SSIZE_MAX");
+__errordecl(__readlink_dest_size_error, "readlink called with size bigger than destination");
+__errordecl(__readlink_size_toobig_error, "readlink called with size > SSIZE_MAX");
+__errordecl(__readlinkat_dest_size_error, "readlinkat called with size bigger than destination");
+__errordecl(__readlinkat_size_toobig_error, "readlinkat called with size > SSIZE_MAX");
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_FORTIFY_INLINE
+char* getcwd(char* buf, size_t size) __overloadable {
+    size_t bos = __bos(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __getcwd_real(buf, size);
+    }
+
+    if (__builtin_constant_p(size) && (size > bos)) {
+        __getcwd_dest_size_error();
+    }
+
+    if (__builtin_constant_p(size) && (size <= bos)) {
+        return __getcwd_real(buf, size);
+    }
+
+    return __getcwd_chk(buf, size, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_M__
+__BIONIC_FORTIFY_INLINE
+ssize_t pread(int fd, void* buf, size_t count, off_t offset) {
+    size_t bos = __bos0(buf);
+
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __PREAD_PREFIX(count_toobig_error)();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __PREAD_PREFIX(real)(fd, buf, count, offset);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __PREAD_PREFIX(dest_size_error)();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __PREAD_PREFIX(real)(fd, buf, count, offset);
+    }
+
+    return __PREAD_PREFIX(chk)(fd, buf, count, offset, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+ssize_t pread64(int fd, void* buf, size_t count, off64_t offset) {
+    size_t bos = __bos0(buf);
+
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __pread64_count_toobig_error();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __pread64_real(fd, buf, count, offset);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __pread64_dest_size_error();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __pread64_real(fd, buf, count, offset);
+    }
+
+    return __pread64_chk(fd, buf, count, offset, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_FORTIFY_INLINE
+ssize_t pwrite(int fd, const void* buf, size_t count, off_t offset) {
+    size_t bos = __bos0(buf);
+
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __PWRITE_PREFIX(count_toobig_error)();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __PWRITE_PREFIX(real)(fd, buf, count, offset);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __PWRITE_PREFIX(dest_size_error)();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __PWRITE_PREFIX(real)(fd, buf, count, offset);
+    }
+
+    return __PWRITE_PREFIX(chk)(fd, buf, count, offset, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+ssize_t pwrite64(int fd, const void* buf, size_t count, off64_t offset) {
+    size_t bos = __bos0(buf);
+
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __pwrite64_count_toobig_error();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __pwrite64_real(fd, buf, count, offset);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __pwrite64_dest_size_error();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __pwrite64_real(fd, buf, count, offset);
+    }
+
+    return __pwrite64_chk(fd, buf, count, offset, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_L__
+__BIONIC_FORTIFY_INLINE
+ssize_t read(int fd, void* buf, size_t count) {
+    size_t bos = __bos0(buf);
+
+    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
+        __read_count_toobig_error();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __read_real(fd, buf, count);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __read_dest_size_error();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __read_real(fd, buf, count);
+    }
+
+    return __read_chk(fd, buf, count, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_N__
+__BIONIC_FORTIFY_INLINE
+ssize_t write(int fd, const void* buf, size_t count) {
+    size_t bos = __bos0(buf);
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __write_real(fd, buf, count);
+    }
+
+    if (__builtin_constant_p(count) && (count > bos)) {
+        __write_dest_size_error();
+    }
+
+    if (__builtin_constant_p(count) && (count <= bos)) {
+        return __write_real(fd, buf, count);
+    }
+
+    return __write_chk(fd, buf, count, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
+
+#if __ANDROID_API__ >= __ANDROID_API_M__
+__BIONIC_FORTIFY_INLINE
+ssize_t readlink(const char* path, char* buf, size_t size) {
+    size_t bos = __bos(buf);
+
+    if (__builtin_constant_p(size) && (size > SSIZE_MAX)) {
+        __readlink_size_toobig_error();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __readlink_real(path, buf, size);
+    }
+
+    if (__builtin_constant_p(size) && (size > bos)) {
+        __readlink_dest_size_error();
+    }
+
+    if (__builtin_constant_p(size) && (size <= bos)) {
+        return __readlink_real(path, buf, size);
+    }
+
+    return __readlink_chk(path, buf, size, bos);
+}
+
+__BIONIC_FORTIFY_INLINE
+ssize_t readlinkat(int dirfd, const char* path, char* buf, size_t size) {
+    size_t bos = __bos(buf);
+
+    if (__builtin_constant_p(size) && (size > SSIZE_MAX)) {
+        __readlinkat_size_toobig_error();
+    }
+
+    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
+        return __readlinkat_real(dirfd, path, buf, size);
+    }
+
+    if (__builtin_constant_p(size) && (size > bos)) {
+        __readlinkat_dest_size_error();
+    }
+
+    if (__builtin_constant_p(size) && (size <= bos)) {
+        return __readlinkat_real(dirfd, path, buf, size);
+    }
+
+    return __readlinkat_chk(dirfd, path, buf, size, bos);
+}
+#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
+#endif /* defined(__clang__) */
+#undef __PREAD_PREFIX
+#undef __PWRITE_PREFIX
+#endif /* defined(__BIONIC_FORTIFY) */
diff --git a/libc/include/fcntl.h b/libc/include/fcntl.h
index f27efdf..cd52b45 100644
--- a/libc/include/fcntl.h
+++ b/libc/include/fcntl.h
@@ -91,120 +91,9 @@
 int sync_file_range(int, off64_t, off64_t, unsigned int) __INTRODUCED_IN(26);
 #endif
 
-int __open_2(const char*, int) __INTRODUCED_IN(17);
-int __openat_2(int, const char*, int) __INTRODUCED_IN(17);
-/*
- * These are the easiest way to call the real open even in clang FORTIFY.
- */
-int __open_real(const char*, int, ...) __RENAME(open);
-int __openat_real(int, const char*, int, ...) __RENAME(openat);
-
-
-#if defined(__BIONIC_FORTIFY)
-#define __open_too_many_args_error "too many arguments"
-#define __open_too_few_args_error "called with O_CREAT, but missing mode"
-#if defined(__clang__)
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int open(const char* pathname, int flags, mode_t modes, ...) __overloadable
-        __errorattr(__open_too_many_args_error);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int open(const char* pathname, int flags) __overloadable
-        __enable_if(flags & O_CREAT, __open_too_few_args_error)
-        __errorattr(__open_too_few_args_error);
-
-/*
- * pass_object_size serves two purposes here, neither of which involve __bos: it
- * disqualifies this function from having its address taken (so &open works),
- * and it makes overload resolution prefer open(const char *, int) over
- * open(const char *, int, ...).
- */
-__BIONIC_FORTIFY_INLINE
-int open(const char* const __pass_object_size pathname,
-         int flags) __overloadable {
-    return __open_2(pathname, flags);
-}
-
-__BIONIC_FORTIFY_INLINE
-int open(const char* const __pass_object_size pathname, int flags, mode_t modes)
-        __overloadable {
-    return __open_real(pathname, flags, modes);
-}
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int openat(int dirfd, const char* pathname, int flags) __overloadable
-        __enable_if(flags & O_CREAT, __open_too_few_args_error)
-        __errorattr(__open_too_few_args_error);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int openat(int dirfd, const char* pathname, int flags, mode_t modes, ...)
-        __overloadable
-        __errorattr(__open_too_many_args_error);
-
-__BIONIC_FORTIFY_INLINE
-int openat(int dirfd, const char* const __pass_object_size pathname,
-           int flags) __overloadable {
-    return __openat_2(dirfd, pathname, flags);
-}
-
-__BIONIC_FORTIFY_INLINE
-int openat(int dirfd, const char* const __pass_object_size pathname, int flags,
-           mode_t modes) __overloadable {
-    return __openat_real(dirfd, pathname, flags, modes);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#else /* defined(__clang__) */
-__errordecl(__creat_missing_mode, __open_too_few_args_error);
-__errordecl(__creat_too_many_args, __open_too_many_args_error);
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE
-int open(const char* pathname, int flags, ...) {
-    if (__builtin_constant_p(flags)) {
-        if ((flags & O_CREAT) && __builtin_va_arg_pack_len() == 0) {
-            __creat_missing_mode();  /* Compile time error. */
-        }
-    }
-
-    if (__builtin_va_arg_pack_len() > 1) {
-        __creat_too_many_args();  /* Compile time error. */
-    }
-
-    if ((__builtin_va_arg_pack_len() == 0) && !__builtin_constant_p(flags)) {
-        return __open_2(pathname, flags);
-    }
-
-    return __open_real(pathname, flags, __builtin_va_arg_pack());
-}
-
-__BIONIC_FORTIFY_INLINE
-int openat(int dirfd, const char* pathname, int flags, ...) {
-    if (__builtin_constant_p(flags)) {
-        if ((flags & O_CREAT) && __builtin_va_arg_pack_len() == 0) {
-            __creat_missing_mode();  /* Compile time error. */
-        }
-    }
-
-    if (__builtin_va_arg_pack_len() > 1) {
-        __creat_too_many_args();  /* Compile time error. */
-    }
-
-    if ((__builtin_va_arg_pack_len() == 0) && !__builtin_constant_p(flags)) {
-        return __openat_2(dirfd, pathname, flags);
-    }
-
-    return __openat_real(dirfd, pathname, flags, __builtin_va_arg_pack());
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#endif /* defined(__clang__) */
-
-#undef __open_too_many_args_error
-#undef __open_too_few_args_error
-#endif /* defined(__BIONIC_FORTIFY) */
+#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
+#include <bits/fortify/fcntl.h>
+#endif
 
 __END_DECLS
 
diff --git a/libc/include/inttypes.h b/libc/include/inttypes.h
index f74afa3..43474df 100644
--- a/libc/include/inttypes.h
+++ b/libc/include/inttypes.h
@@ -257,10 +257,10 @@
 __BEGIN_DECLS
 intmax_t imaxabs(intmax_t) __attribute_const__ __INTRODUCED_IN(19);
 imaxdiv_t imaxdiv(intmax_t, intmax_t) __attribute_const__ __INTRODUCED_IN(19);
-intmax_t	strtoimax(const char *, char **, int);
-uintmax_t	strtoumax(const char *, char **, int);
-intmax_t wcstoimax(const wchar_t* __restrict, wchar_t** __restrict, int) __INTRODUCED_IN(21);
-uintmax_t wcstoumax(const wchar_t* __restrict, wchar_t** __restrict, int) __INTRODUCED_IN(21);
+intmax_t strtoimax(const char*, char**, int);
+uintmax_t strtoumax(const char*, char**, int);
+intmax_t wcstoimax(const wchar_t*, wchar_t**, int) __INTRODUCED_IN(21);
+uintmax_t wcstoumax(const wchar_t*, wchar_t**, int) __INTRODUCED_IN(21);
 __END_DECLS
 
 #endif /* _INTTYPES_H_ */
diff --git a/libc/include/poll.h b/libc/include/poll.h
index 3287a0c..0f5758d 100644
--- a/libc/include/poll.h
+++ b/libc/include/poll.h
@@ -42,87 +42,9 @@
 int ppoll(struct pollfd*, nfds_t, const struct timespec*, const sigset_t*)
         __overloadable __RENAME_CLANG(ppoll) __INTRODUCED_IN(21);
 
-int __poll_chk(struct pollfd*, nfds_t, int, size_t) __INTRODUCED_IN(23);
-int __ppoll_chk(struct pollfd*, nfds_t, const struct timespec*, const sigset_t*, size_t)
-  __INTRODUCED_IN(23);
-
-#if defined(__BIONIC_FORTIFY)
-#if __ANDROID_API__ >= __ANDROID_API_M__
-#if defined(__clang__)
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int poll(struct pollfd* fds, nfds_t fd_count, int timeout) __overloadable
-        __enable_if(__bos(fds) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                    __bos(fds) < sizeof(*fds) * fd_count,
-                    "selected when there aren't fd_count fds")
-        __errorattr("too many fds specified");
-
-__BIONIC_FORTIFY_INLINE
-int poll(struct pollfd* const fds __pass_object_size, nfds_t fd_count,
-        int timeout) __overloadable {
-  size_t bos_fds = __bos(fds);
-
-  if (bos_fds == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-      return __call_bypassing_fortify(poll)(fds, fd_count, timeout);
-  }
-
-  return __poll_chk(fds, fd_count, timeout, bos_fds);
-}
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int ppoll(struct pollfd* fds, nfds_t fd_count, const struct timespec* timeout,
-          const sigset_t* mask)  __overloadable
-        __enable_if(__bos(fds) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                    __bos(fds) < sizeof(*fds) * fd_count,
-                    "selected when there aren't fd_count fds")
-        __errorattr("too many fds specified");
-
-__BIONIC_FORTIFY_INLINE
-int ppoll(struct pollfd* const fds __pass_object_size, nfds_t fd_count,
-          const struct timespec* timeout, const sigset_t* mask) __overloadable {
-  size_t bos_fds = __bos(fds);
-
-  if (bos_fds == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-      return __call_bypassing_fortify(ppoll)(fds, fd_count, timeout, mask);
-  }
-
-  return __ppoll_chk(fds, fd_count, timeout, mask, bos_fds);
-}
-#else /* defined(__clang__) */
-int __poll_real(struct pollfd*, nfds_t, int) __RENAME(poll);
-__errordecl(__poll_too_small_error, "poll: pollfd array smaller than fd count");
-
-int __ppoll_real(struct pollfd*, nfds_t, const struct timespec*, const sigset_t*) __RENAME(ppoll)
-  __INTRODUCED_IN(21);
-__errordecl(__ppoll_too_small_error, "ppoll: pollfd array smaller than fd count");
-
-__BIONIC_FORTIFY_INLINE
-int poll(struct pollfd* fds, nfds_t fd_count, int timeout) {
-  if (__bos(fds) != __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-    if (!__builtin_constant_p(fd_count)) {
-      return __poll_chk(fds, fd_count, timeout, __bos(fds));
-    } else if (__bos(fds) / sizeof(*fds) < fd_count) {
-      __poll_too_small_error();
-    }
-  }
-  return __poll_real(fds, fd_count, timeout);
-}
-
-__BIONIC_FORTIFY_INLINE
-int ppoll(struct pollfd* fds, nfds_t fd_count, const struct timespec* timeout,
-          const sigset_t* mask) {
-  if (__bos(fds) != __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-    if (!__builtin_constant_p(fd_count)) {
-      return __ppoll_chk(fds, fd_count, timeout, mask, __bos(fds));
-    } else if (__bos(fds) / sizeof(*fds) < fd_count) {
-      __ppoll_too_small_error();
-    }
-  }
-  return __ppoll_real(fds, fd_count, timeout, mask);
-}
-
-#endif /* defined(__clang__) */
-#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
-#endif /* defined(__BIONIC_FORTIFY) */
+#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
+#include <bits/fortify/poll.h>
+#endif
 
 __END_DECLS
 
diff --git a/libc/include/search.h b/libc/include/search.h
index dc160e9..46998d9 100644
--- a/libc/include/search.h
+++ b/libc/include/search.h
@@ -37,7 +37,7 @@
 void* lsearch(const void*, void*, size_t*, size_t, int (*)(const void*, const void*))
   __INTRODUCED_IN(21);
 
-void* tdelete(const void* __restrict, void** __restrict, int (*)(const void*, const void*))
+void* tdelete(const void*, void**, int (*)(const void*, const void*))
   __INTRODUCED_IN(16);
 void tdestroy(void*, void (*)(void*)) __INTRODUCED_IN(16);
 void* tfind(const void*, void* const*, int (*)(const void*, const void*)) __INTRODUCED_IN(16);
diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index 72f83fb..327bdc2 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -120,39 +120,39 @@
 int	 ferror(FILE *);
 int	 fflush(FILE *);
 int	 fgetc(FILE *);
-char	*fgets(char * __restrict, int, FILE * __restrict) __overloadable
+char	*fgets(char *, int, FILE *) __overloadable
   __RENAME_CLANG(fgets);
-int	 fprintf(FILE * __restrict , const char * __restrict _Nonnull, ...) __printflike(2, 3);
+int	 fprintf(FILE * , const char * _Nonnull, ...) __printflike(2, 3);
 int	 fputc(int, FILE *);
-int	 fputs(const char * __restrict, FILE * __restrict);
-size_t	 fread(void * __restrict, size_t, size_t, FILE * __restrict)
+int	 fputs(const char *, FILE *);
+size_t	 fread(void *, size_t, size_t, FILE *)
       __overloadable __RENAME_CLANG(fread);
-int	 fscanf(FILE * __restrict, const char * __restrict _Nonnull, ...) __scanflike(2, 3);
-size_t	 fwrite(const void * __restrict, size_t, size_t, FILE * __restrict)
+int	 fscanf(FILE *, const char * _Nonnull, ...) __scanflike(2, 3);
+size_t	 fwrite(const void *, size_t, size_t, FILE *)
     __overloadable __RENAME_CLANG(fwrite);
 int	 getc(FILE *);
 int	 getchar(void);
-ssize_t getdelim(char** __restrict, size_t* __restrict, int, FILE* __restrict) __INTRODUCED_IN(18);
-ssize_t getline(char** __restrict, size_t* __restrict, FILE* __restrict) __INTRODUCED_IN(18);
+ssize_t getdelim(char**, size_t*, int, FILE*) __INTRODUCED_IN(18);
+ssize_t getline(char**, size_t*, FILE*) __INTRODUCED_IN(18);
 
 void	 perror(const char *);
-int	 printf(const char * __restrict _Nonnull, ...) __printflike(1, 2);
+int	 printf(const char * _Nonnull, ...) __printflike(1, 2);
 int	 putc(int, FILE *);
 int	 putchar(int);
 int	 puts(const char *);
 int	 remove(const char *);
 void	 rewind(FILE *);
-int	 scanf(const char * __restrict _Nonnull, ...) __scanflike(1, 2);
-void	 setbuf(FILE * __restrict, char * __restrict);
-int	 setvbuf(FILE * __restrict, char * __restrict, int, size_t);
-int	 sscanf(const char * __restrict, const char * __restrict _Nonnull, ...) __scanflike(2, 3);
+int	 scanf(const char * _Nonnull, ...) __scanflike(1, 2);
+void	 setbuf(FILE *, char *);
+int	 setvbuf(FILE *, char *, int, size_t);
+int	 sscanf(const char *, const char * _Nonnull, ...) __scanflike(2, 3);
 int	 ungetc(int, FILE *);
-int	 vfprintf(FILE * __restrict, const char * __restrict _Nonnull, __va_list) __printflike(2, 0);
-int	 vprintf(const char * __restrict _Nonnull, __va_list) __printflike(1, 0);
+int	 vfprintf(FILE *, const char * _Nonnull, __va_list) __printflike(2, 0);
+int	 vprintf(const char * _Nonnull, __va_list) __printflike(1, 0);
 
 #if __ANDROID_API__ >= 21
-int dprintf(int, const char* __restrict _Nonnull, ...) __printflike(2, 3) __INTRODUCED_IN(21);
-int vdprintf(int, const char* __restrict _Nonnull, __va_list) __printflike(2, 0) __INTRODUCED_IN(21);
+int dprintf(int, const char* _Nonnull, ...) __printflike(2, 3) __INTRODUCED_IN(21);
+int vdprintf(int, const char* _Nonnull, __va_list) __printflike(2, 0) __INTRODUCED_IN(21);
 #else
 /*
  * Old versions of Android called these fdprintf and vfdprintf out of fears that the glibc names
@@ -161,18 +161,18 @@
  * Allow users to just use dprintf and vfdprintf on any version by renaming those calls to their
  * legacy equivalents if needed.
  */
-int dprintf(int, const char* __restrict _Nonnull, ...) __printflike(2, 3) __RENAME(fdprintf);
-int vdprintf(int, const char* __restrict _Nonnull, __va_list) __printflike(2, 0) __RENAME(vfdprintf);
+int dprintf(int, const char* _Nonnull, ...) __printflike(2, 3) __RENAME(fdprintf);
+int vdprintf(int, const char* _Nonnull, __va_list) __printflike(2, 0) __RENAME(vfdprintf);
 #endif
 
 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ < 201112L) || \
     (defined(__cplusplus) && __cplusplus <= 201103L)
 char* gets(char*) __attribute__((deprecated("gets is unsafe, use fgets instead")));
 #endif
-int sprintf(char* __restrict, const char* __restrict _Nonnull, ...)
+int sprintf(char*, const char* _Nonnull, ...)
     __printflike(2, 3) __warnattr_strict("sprintf is often misused; please use snprintf")
     __overloadable __RENAME_CLANG(sprintf);
-int vsprintf(char* __restrict, const char* __restrict _Nonnull, __va_list)
+int vsprintf(char*, const char* _Nonnull, __va_list)
     __overloadable __printflike(2, 0) __RENAME_CLANG(vsprintf)
     __warnattr_strict("vsprintf is often misused; please use vsnprintf");
 char* tmpnam(char*)
@@ -221,21 +221,21 @@
                 fpos64_t (*)(void*, fpos64_t, int), int (*)(void*)) __INTRODUCED_IN(24);
 #endif
 
-FILE* fopen(const char* __restrict, const char* __restrict);
-FILE* fopen64(const char* __restrict, const char* __restrict) __INTRODUCED_IN(24);
-FILE* freopen(const char* __restrict, const char* __restrict, FILE* __restrict);
-FILE* freopen64(const char* __restrict, const char* __restrict, FILE* __restrict)
+FILE* fopen(const char*, const char*);
+FILE* fopen64(const char*, const char*) __INTRODUCED_IN(24);
+FILE* freopen(const char*, const char*, FILE*);
+FILE* freopen64(const char*, const char*, FILE*)
   __INTRODUCED_IN(24);
 FILE* tmpfile(void);
 FILE* tmpfile64(void) __INTRODUCED_IN(24);
 
-int snprintf(char* __restrict, size_t, const char* __restrict _Nonnull, ...)
+int snprintf(char*, size_t, const char* _Nonnull, ...)
     __printflike(3, 4) __overloadable __RENAME_CLANG(snprintf);
-int vfscanf(FILE* __restrict, const char* __restrict _Nonnull, __va_list) __scanflike(2, 0);
+int vfscanf(FILE*, const char* _Nonnull, __va_list) __scanflike(2, 0);
 int vscanf(const char* _Nonnull , __va_list) __scanflike(1, 0);
-int vsnprintf(char* __restrict, size_t, const char* __restrict _Nonnull, __va_list)
+int vsnprintf(char*, size_t, const char* _Nonnull, __va_list)
     __printflike(3, 0) __overloadable __RENAME_CLANG(vsnprintf);
-int vsscanf(const char* __restrict _Nonnull, const char* __restrict _Nonnull, __va_list) __scanflike(2, 0);
+int vsscanf(const char* _Nonnull, const char* _Nonnull, __va_list) __scanflike(2, 0);
 
 #define L_ctermid 1024 /* size for ctermid() */
 char* ctermid(char*) __INTRODUCED_IN(26);
@@ -256,12 +256,12 @@
 FILE* open_memstream(char**, size_t*) __INTRODUCED_IN(23);
 
 #if defined(__USE_BSD) || defined(__BIONIC__) /* Historically bionic exposed these. */
-int  asprintf(char** __restrict, const char* __restrict _Nonnull, ...) __printflike(2, 3);
-char* fgetln(FILE* __restrict, size_t* __restrict);
+int  asprintf(char**, const char* _Nonnull, ...) __printflike(2, 3);
+char* fgetln(FILE*, size_t*);
 int fpurge(FILE*);
 void setbuffer(FILE*, char*, int);
 int setlinebuf(FILE*);
-int vasprintf(char** __restrict, const char* __restrict _Nonnull, __va_list) __printflike(2, 0);
+int vasprintf(char**, const char* _Nonnull, __va_list) __printflike(2, 0);
 void clearerr_unlocked(FILE*) __INTRODUCED_IN(23);
 int feof_unlocked(FILE*) __INTRODUCED_IN(23);
 int ferror_unlocked(FILE*) __INTRODUCED_IN(23);
@@ -270,265 +270,9 @@
 #define fwopen(cookie, fn) funopen(cookie, 0, fn, 0, 0)
 #endif /* __USE_BSD */
 
-char* __fgets_chk(char*, int, FILE*, size_t) __INTRODUCED_IN(17);
-size_t __fread_chk(void* __restrict, size_t, size_t, FILE* __restrict, size_t)
-    __INTRODUCED_IN(24);
-size_t __fwrite_chk(const void* __restrict, size_t, size_t, FILE* __restrict, size_t)
-    __INTRODUCED_IN(24);
-
-#if defined(__BIONIC_FORTIFY) && !defined(__BIONIC_NO_STDIO_FORTIFY)
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE __printflike(3, 0)
-int vsnprintf(char *const __pass_object_size dest, size_t size,
-              const char *_Nonnull format, __va_list ap) __overloadable {
-    return __builtin___vsnprintf_chk(dest, size, 0, __bos(dest), format, ap);
-}
-
-__BIONIC_FORTIFY_INLINE __printflike(2, 0)
-int vsprintf(char *const __pass_object_size dest, const char *_Nonnull format,
-             __va_list ap) __overloadable {
-    return __builtin___vsprintf_chk(dest, 0, __bos(dest), format, ap);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#if defined(__clang__)
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-/*
- * Simple case: `format` can't have format specifiers, so we can just compare
- * its length to the length of `dest`
- */
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int snprintf(char *__restrict dest, size_t size, const char *__restrict format)
-    __overloadable
-    __enable_if(__bos(dest) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                __bos(dest) < __builtin_strlen(format),
-                "format string will always overflow destination buffer")
-    __errorattr("format string will always overflow destination buffer");
-
-__BIONIC_FORTIFY_INLINE
-__printflike(3, 4)
-int snprintf(char *__restrict const __pass_object_size dest,
-             size_t size, const char *__restrict format, ...) __overloadable {
-    va_list va;
-    va_start(va, format);
-    int result = __builtin___vsnprintf_chk(dest, size, 0, __bos(dest), format, va);
-    va_end(va);
-    return result;
-}
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-int sprintf(char *__restrict dest, const char *__restrict format) __overloadable
-    __enable_if(__bos(dest) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                __bos(dest) < __builtin_strlen(format),
-                "format string will always overflow destination buffer")
-    __errorattr("format string will always overflow destination buffer");
-
-__BIONIC_FORTIFY_INLINE
-__printflike(2, 3)
-int sprintf(char *__restrict const __pass_object_size dest,
-        const char *__restrict format, ...) __overloadable {
-    va_list va;
-    va_start(va, format);
-    int result = __builtin___vsprintf_chk(dest, 0, __bos(dest), format, va);
-    va_end(va);
-    return result;
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_FORTIFY_INLINE
-size_t fread(void *__restrict buf, size_t size, size_t count,
-             FILE *__restrict stream) __overloadable
-        __enable_if(__unsafe_check_mul_overflow(size, count), "size * count overflows")
-        __errorattr("size * count overflows");
-
-__BIONIC_FORTIFY_INLINE
-size_t fread(void *__restrict buf, size_t size, size_t count,
-             FILE *__restrict stream) __overloadable
-    __enable_if(!__unsafe_check_mul_overflow(size, count), "no overflow")
-    __enable_if(__bos(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                size * count > __bos(buf), "size * count is too large")
-    __errorattr("size * count is too large");
-
-__BIONIC_FORTIFY_INLINE
-size_t fread(void *__restrict const __pass_object_size0 buf, size_t size,
-             size_t count, FILE *__restrict stream) __overloadable {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(fread)(buf, size, count, stream);
-    }
-
-    return __fread_chk(buf, size, count, stream, bos);
-}
-
-size_t fwrite(const void * __restrict buf, size_t size,
-              size_t count, FILE * __restrict stream) __overloadable
-    __enable_if(__unsafe_check_mul_overflow(size, count),
-                "size * count overflows")
-    __errorattr("size * count overflows");
-
-size_t fwrite(const void * __restrict buf, size_t size,
-              size_t count, FILE * __restrict stream) __overloadable
-    __enable_if(!__unsafe_check_mul_overflow(size, count), "no overflow")
-    __enable_if(__bos(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                size * count > __bos(buf), "size * count is too large")
-    __errorattr("size * count is too large");
-
-__BIONIC_FORTIFY_INLINE
-size_t fwrite(const void * __restrict const __pass_object_size0 buf,
-              size_t size, size_t count, FILE * __restrict stream)
-        __overloadable {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(fwrite)(buf, size, count, stream);
-    }
-
-    return __fwrite_chk(buf, size, count, stream, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-char *fgets(char* __restrict dest, int size, FILE* stream) __overloadable
-    __enable_if(size < 0, "size is negative")
-    __errorattr("size is negative");
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-char *fgets(char* dest, int size, FILE* stream) __overloadable
-    __enable_if(size >= 0 && size > __bos(dest),
-                "size is larger than the destination buffer")
-    __errorattr("size is larger than the destination buffer");
-
-__BIONIC_FORTIFY_INLINE
-char *fgets(char* __restrict const __pass_object_size dest,
-        int size, FILE* stream) __overloadable {
-    size_t bos = __bos(dest);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(fgets)(dest, size, stream);
-    }
-
-    return __fgets_chk(dest, size, stream, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#else /* defined(__clang__) */
-
-size_t __fread_real(void * __restrict, size_t, size_t, FILE * __restrict) __RENAME(fread);
-__errordecl(__fread_too_big_error, "fread called with size * count bigger than buffer");
-__errordecl(__fread_overflow, "fread called with overflowing size * count");
-
-char* __fgets_real(char*, int, FILE*) __RENAME(fgets);
-__errordecl(__fgets_too_big_error, "fgets called with size bigger than buffer");
-__errordecl(__fgets_too_small_error, "fgets called with size less than zero");
-
-size_t __fwrite_real(const void * __restrict, size_t, size_t, FILE * __restrict) __RENAME(fwrite);
-__errordecl(__fwrite_too_big_error, "fwrite called with size * count bigger than buffer");
-__errordecl(__fwrite_overflow, "fwrite called with overflowing size * count");
-
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE __printflike(3, 4)
-int snprintf(char *__restrict dest, size_t size, const char* _Nonnull format, ...)
-{
-    return __builtin___snprintf_chk(dest, size, 0, __bos(dest), format,
-                                    __builtin_va_arg_pack());
-}
-
-__BIONIC_FORTIFY_INLINE __printflike(2, 3)
-int sprintf(char *__restrict dest, const char* _Nonnull format, ...) {
-    return __builtin___sprintf_chk(dest, 0, __bos(dest), format,
-                                   __builtin_va_arg_pack());
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_FORTIFY_INLINE
-size_t fread(void *__restrict buf, size_t size, size_t count, FILE * __restrict stream) {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __fread_real(buf, size, count, stream);
-    }
-
-    if (__builtin_constant_p(size) && __builtin_constant_p(count)) {
-        size_t total;
-        if (__size_mul_overflow(size, count, &total)) {
-            __fread_overflow();
-        }
-
-        if (total > bos) {
-            __fread_too_big_error();
-        }
-
-        return __fread_real(buf, size, count, stream);
-    }
-
-    return __fread_chk(buf, size, count, stream, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-size_t fwrite(const void * __restrict buf, size_t size, size_t count, FILE * __restrict stream) {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __fwrite_real(buf, size, count, stream);
-    }
-
-    if (__builtin_constant_p(size) && __builtin_constant_p(count)) {
-        size_t total;
-        if (__size_mul_overflow(size, count, &total)) {
-            __fwrite_overflow();
-        }
-
-        if (total > bos) {
-            __fwrite_too_big_error();
-        }
-
-        return __fwrite_real(buf, size, count, stream);
-    }
-
-    return __fwrite_chk(buf, size, count, stream, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE
-char *fgets(char* dest, int size, FILE* stream) {
-    size_t bos = __bos(dest);
-
-    // Compiler can prove, at compile time, that the passed in size
-    // is always negative. Force a compiler error.
-    if (__builtin_constant_p(size) && (size < 0)) {
-        __fgets_too_small_error();
-    }
-
-    // Compiler doesn't know destination size. Don't call __fgets_chk
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __fgets_real(dest, size, stream);
-    }
-
-    // Compiler can prove, at compile time, that the passed in size
-    // is always <= the actual object size. Don't call __fgets_chk
-    if (__builtin_constant_p(size) && (size <= (int) bos)) {
-        return __fgets_real(dest, size, stream);
-    }
-
-    // Compiler can prove, at compile time, that the passed in size
-    // is always > the actual object size. Force a compiler error.
-    if (__builtin_constant_p(size) && (size > (int) bos)) {
-        __fgets_too_big_error();
-    }
-
-    return __fgets_chk(dest, size, stream, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#endif /* defined(__clang__) */
-#endif /* defined(__BIONIC_FORTIFY) */
+#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
+#include <bits/fortify/stdio.h>
+#endif
 
 #if defined(__clang__)
 #pragma clang diagnostic pop
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 24ddd99..55e0fa2 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -165,46 +165,9 @@
 #define MB_CUR_MAX 1
 #endif
 
-#if defined(__BIONIC_FORTIFY)
-#define __realpath_buf_too_small_str \
-    "realpath output parameter must be NULL or a >= PATH_MAX bytes buffer"
-
-/* PATH_MAX is unavailable without polluting the namespace, but it's always 4096 on Linux */
-#define __PATH_MAX 4096
-
-#if defined(__clang__)
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-char* realpath(const char* path, char* resolved) __overloadable
-    __enable_if(__bos(resolved) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                __bos(resolved) < __PATH_MAX, __realpath_buf_too_small_str)
-    __errorattr(__realpath_buf_too_small_str);
-
-/* No need for a FORTIFY version; the only things we can catch are at
- * compile-time.
- */
-
-#else /* defined(__clang__) */
-
-char* __realpath_real(const char*, char*) __RENAME(realpath);
-__errordecl(__realpath_size_error, __realpath_buf_too_small_str);
-
-__BIONIC_FORTIFY_INLINE
-char* realpath(const char* path, char* resolved) {
-    size_t bos = __bos(resolved);
-
-    if (bos != __BIONIC_FORTIFY_UNKNOWN_SIZE && bos < __PATH_MAX) {
-        __realpath_size_error();
-    }
-
-    return __realpath_real(path, resolved);
-}
-
-#endif /* defined(__clang__) */
-
-#undef __PATH_MAX
-#undef __realpath_buf_too_small_str
-#endif /* defined(__BIONIC_FORTIFY) */
+#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
+#include <bits/fortify/stdlib.h>
+#endif
 
 #if __ANDROID_API__ >= __ANDROID_API_L__
 float strtof(const char*, char**) __INTRODUCED_IN(21);
diff --git a/libc/include/string.h b/libc/include/string.h
index c15fe4a..8b4fa27 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -46,16 +46,16 @@
 #include <strings.h>
 #endif
 
-void* memccpy(void* _Nonnull __restrict, const void* _Nonnull __restrict, int, size_t);
+void* memccpy(void* _Nonnull, const void* _Nonnull, int, size_t);
 void* memchr(const void* _Nonnull, int, size_t) __attribute_pure__ __overloadable
         __RENAME_CLANG(memchr);
 void* memrchr(const void* _Nonnull, int, size_t) __attribute_pure__ __overloadable
         __RENAME_CLANG(memrchr);
 int memcmp(const void* _Nonnull, const void* _Nonnull, size_t) __attribute_pure__;
-void* memcpy(void* _Nonnull __restrict, const void* _Nonnull __restrict, size_t)
+void* memcpy(void* _Nonnull, const void* _Nonnull, size_t)
         __overloadable __RENAME_CLANG(memcpy);
 #if defined(__USE_GNU)
-void* mempcpy(void* _Nonnull __restrict, const void* _Nonnull __restrict, size_t) __INTRODUCED_IN(23);
+void* mempcpy(void* _Nonnull, const void* _Nonnull, size_t) __INTRODUCED_IN(23);
 #endif
 void* memmove(void* _Nonnull, const void* _Nonnull, size_t) __overloadable
         __RENAME_CLANG(memmove);
@@ -83,18 +83,18 @@
 size_t __strlen_chk(const char* _Nonnull, size_t) __INTRODUCED_IN(17);
 
 int strcmp(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
-char* stpcpy(char* _Nonnull __restrict, const char* _Nonnull __restrict)
+char* stpcpy(char* _Nonnull, const char* _Nonnull)
         __overloadable __RENAME_CLANG(stpcpy) __INTRODUCED_IN(21);
-char* strcpy(char* _Nonnull __restrict, const char* _Nonnull __restrict)
+char* strcpy(char* _Nonnull, const char* _Nonnull)
         __overloadable __RENAME_CLANG(strcpy);
-char* strcat(char* _Nonnull __restrict, const char* _Nonnull __restrict)
+char* strcat(char* _Nonnull, const char* _Nonnull)
         __overloadable __RENAME_CLANG(strcat);
 char* strdup(const char* _Nonnull);
 
 char* strstr(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
 char* strcasestr(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
-char* strtok(char* __restrict, const char* _Nonnull __restrict);
-char* strtok_r(char* __restrict, const char* _Nonnull __restrict, char** _Nonnull __restrict);
+char* strtok(char*, const char* _Nonnull);
+char* strtok_r(char*, const char* _Nonnull, char** _Nonnull);
 
 char* strerror(int);
 char* strerror_l(int, locale_t) __INTRODUCED_IN(23);
@@ -105,33 +105,33 @@
 #endif
 
 size_t strnlen(const char* _Nonnull, size_t) __attribute_pure__;
-char* strncat(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t)
+char* strncat(char* _Nonnull, const char* _Nonnull, size_t)
         __overloadable __RENAME_CLANG(strncat);
 char* strndup(const char* _Nonnull, size_t);
 int strncmp(const char* _Nonnull, const char* _Nonnull, size_t) __attribute_pure__;
-char* stpncpy(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t)
+char* stpncpy(char* _Nonnull, const char* _Nonnull, size_t)
         __overloadable __RENAME_CLANG(stpncpy) __INTRODUCED_IN(21);
-char* strncpy(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t)
+char* strncpy(char* _Nonnull, const char* _Nonnull, size_t)
         __overloadable __RENAME_CLANG(strncpy);
 
-size_t strlcat(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t)
+size_t strlcat(char* _Nonnull, const char* _Nonnull, size_t)
         __overloadable __RENAME_CLANG(strlcat);
-size_t strlcpy(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t)
+size_t strlcpy(char* _Nonnull, const char* _Nonnull, size_t)
         __overloadable __RENAME_CLANG(strlcpy);
 
 size_t strcspn(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
 char* strpbrk(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
-char* strsep(char** _Nonnull __restrict, const char* _Nonnull __restrict);
+char* strsep(char** _Nonnull, const char* _Nonnull);
 size_t strspn(const char* _Nonnull, const char* _Nonnull);
 
 char* strsignal(int);
 
 int strcoll(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
-size_t strxfrm(char* __restrict, const char* _Nonnull __restrict, size_t);
+size_t strxfrm(char*, const char* _Nonnull, size_t);
 
 #if __ANDROID_API__ >= __ANDROID_API_L__
 int strcoll_l(const char* _Nonnull, const char* _Nonnull, locale_t) __attribute_pure__ __INTRODUCED_IN(21);
-size_t strxfrm_l(char* __restrict, const char* _Nonnull __restrict, size_t, locale_t) __INTRODUCED_IN(21);
+size_t strxfrm_l(char*, const char* _Nonnull, size_t, locale_t) __INTRODUCED_IN(21);
 #else
 // Implemented as static inlines before 21.
 #endif
@@ -149,455 +149,9 @@
 #endif
 #endif
 
-void* __memchr_chk(const void* _Nonnull, int, size_t, size_t) __INTRODUCED_IN(23);
-void* __memrchr_chk(const void* _Nonnull, int, size_t, size_t) __INTRODUCED_IN(23);
-char* __stpncpy_chk2(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t, size_t, size_t)
-  __INTRODUCED_IN(21);
-char* __strncpy_chk2(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t, size_t, size_t)
-  __INTRODUCED_IN(21);
-size_t __strlcpy_chk(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t, size_t) __INTRODUCED_IN(17);
-size_t __strlcat_chk(char* _Nonnull __restrict, const char* _Nonnull __restrict, size_t, size_t) __INTRODUCED_IN(17);
-
-/* Only used with FORTIFY, but some headers that need it undef FORTIFY, so we
- * have the definition out here.
- */
-struct __bionic_zero_size_is_okay_t {};
-
-#if defined(__BIONIC_FORTIFY)
-// These can share their implementation between gcc and clang with minimal
-// trickery...
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE
-void* memcpy(void* _Nonnull __restrict const dst __pass_object_size0, const void* _Nonnull __restrict src, size_t copy_amount)
-        __overloadable {
-    return __builtin___memcpy_chk(dst, src, copy_amount, __bos0(dst));
-}
-
-__BIONIC_FORTIFY_INLINE
-void* memmove(void* const _Nonnull dst __pass_object_size0, const void* _Nonnull src, size_t len)
-        __overloadable {
-    return __builtin___memmove_chk(dst, src, len, __bos0(dst));
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_L__
-__BIONIC_FORTIFY_INLINE
-char* stpcpy(char* _Nonnull __restrict const dst __pass_object_size, const char* _Nonnull __restrict src)
-        __overloadable {
-    return __builtin___stpcpy_chk(dst, src, __bos(dst));
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE
-char* strcpy(char* _Nonnull __restrict const dst __pass_object_size, const char* _Nonnull __restrict src)
-        __overloadable {
-    return __builtin___strcpy_chk(dst, src, __bos(dst));
-}
-
-__BIONIC_FORTIFY_INLINE
-char* strcat(char* _Nonnull __restrict const dst __pass_object_size, const char* _Nonnull __restrict src)
-        __overloadable {
-    return __builtin___strcat_chk(dst, src, __bos(dst));
-}
-
-__BIONIC_FORTIFY_INLINE
-char* strncat(char* const _Nonnull __restrict dst __pass_object_size, const char* _Nonnull __restrict src, size_t n)
-        __overloadable {
-    return __builtin___strncat_chk(dst, src, n, __bos(dst));
-}
-
-__BIONIC_FORTIFY_INLINE
-void* memset(void* const _Nonnull s __pass_object_size0, int c, size_t n) __overloadable {
-    return __builtin___memset_chk(s, c, n, __bos0(s));
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-
-#if defined(__clang__)
-
-#define __error_if_overflows_dst(name, dst, n, what) \
-    __enable_if(__bos0(dst) != __BIONIC_FORTIFY_UNKNOWN_SIZE && \
-                __bos0(dst) < (n), "selected when the buffer is too small") \
-    __errorattr(#name " called with " what " bigger than buffer")
-
-/*
- * N.B. _Nonnull isn't necessary on params, since these functions just emit
- * errors.
- */
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-void* memcpy(void* dst, const void* src, size_t copy_amount) __overloadable
-        __error_if_overflows_dst(memcpy, dst, copy_amount, "size");
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-void* memmove(void *dst, const void* src, size_t len) __overloadable
-        __error_if_overflows_dst(memmove, dst, len, "size");
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-void* memset(void* s, int c, size_t n) __overloadable
-        __error_if_overflows_dst(memset, s, n, "size");
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-char* stpcpy(char* dst, const char* src) __overloadable
-        __error_if_overflows_dst(stpcpy, dst, __builtin_strlen(src), "string");
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-char* strcpy(char* dst, const char* src) __overloadable
-        __error_if_overflows_dst(strcpy, dst, __builtin_strlen(src), "string");
-
-#if __ANDROID_API__ >= __ANDROID_API_M__
-__BIONIC_FORTIFY_INLINE
-void* memchr(const void* const _Nonnull s __pass_object_size, int c, size_t n)
-        __overloadable {
-    size_t bos = __bos(s);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin_memchr(s, c, n);
-    }
-
-    return __memchr_chk(s, c, n, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-void* memrchr(const void* const _Nonnull s __pass_object_size, int c, size_t n)
-        __overloadable {
-    size_t bos = __bos(s);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(memrchr)(s, c, n);
-    }
-
-    return __memrchr_chk(s, c, n, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_L__
-__BIONIC_FORTIFY_INLINE
-char* stpncpy(char* __restrict const _Nonnull dst __pass_object_size, const char* __restrict const _Nonnull src __pass_object_size, size_t n)
-        __overloadable {
-    size_t bos_dst = __bos(dst);
-    size_t bos_src = __bos(src);
-
-    /* Ignore dst size checks; they're handled in strncpy_chk */
-    if (bos_src == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin___stpncpy_chk(dst, src, n, bos_dst);
-    }
-
-    return __stpncpy_chk2(dst, src, n, bos_dst, bos_src);
-}
-
-__BIONIC_FORTIFY_INLINE
-char* strncpy(char* __restrict const _Nonnull dst __pass_object_size, const char* __restrict const _Nonnull src __pass_object_size, size_t n)
-        __overloadable {
-    size_t bos_dst = __bos(dst);
-    size_t bos_src = __bos(src);
-
-    /* Ignore dst size checks; they're handled in strncpy_chk */
-    if (bos_src == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin___strncpy_chk(dst, src, n, bos_dst);
-    }
-
-    return __strncpy_chk2(dst, src, n, bos_dst, bos_src);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE
-size_t strlcpy(char* const _Nonnull __restrict dst __pass_object_size, const char *_Nonnull __restrict src, size_t size)
-        __overloadable {
-    size_t bos = __bos(dst);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(strlcpy)(dst, src, size);
-    }
-
-    return __strlcpy_chk(dst, src, size, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-size_t strlcat(char* const _Nonnull __restrict dst __pass_object_size, const char* _Nonnull __restrict src, size_t size)
-        __overloadable {
-    size_t bos = __bos(dst);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(strlcat)(dst, src, size);
-    }
-
-    return __strlcat_chk(dst, src, size, bos);
-}
-
-/*
- * If we can evaluate the size of s at compile-time, just call __builtin_strlen
- * on it directly. This makes it way easier for compilers to fold things like
- * strlen("Foo") into a constant, as users would expect. -1ULL is chosen simply
- * because it's large.
- */
-__BIONIC_FORTIFY_INLINE
-size_t strlen(const char* const _Nonnull s __pass_object_size)
-        __overloadable __enable_if(__builtin_strlen(s) != -1ULL,
-                                   "enabled if s is a known good string.") {
-    return __builtin_strlen(s);
-}
-
-__BIONIC_FORTIFY_INLINE
-size_t strlen(const char* const _Nonnull s __pass_object_size0)
-        __overloadable {
-    size_t bos = __bos0(s);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin_strlen(s);
-    }
-
-    // return __builtin_strlen(s);
-    return __strlen_chk(s, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#if  __ANDROID_API__ >= __ANDROID_API_J_MR2__
-__BIONIC_FORTIFY_INLINE
-char* strchr(const char* const _Nonnull s __pass_object_size, int c)
-        __overloadable {
-    size_t bos = __bos(s);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin_strchr(s, c);
-    }
-
-    return __strchr_chk(s, c, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-char* strrchr(const char* const _Nonnull s __pass_object_size, int c)
-        __overloadable {
-    size_t bos = __bos(s);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin_strrchr(s, c);
-    }
-
-    return __strrchr_chk(s, c, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-/* In *many* cases, memset(foo, sizeof(foo), 0) is a mistake where the user has
- * flipped the size + value arguments. However, there may be cases (e.g. with
- * macros) where it's okay for the size to fold to zero. We should warn on this,
- * but we should also provide a FORTIFY'ed escape hatch.
- */
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-void* memset(void* _Nonnull s, int c, size_t n, struct __bionic_zero_size_is_okay_t ok)
-        __overloadable
-        __error_if_overflows_dst(memset, s, n, "size");
-
-__BIONIC_FORTIFY_INLINE
-void* memset(void* const _Nonnull s __pass_object_size0, int c, size_t n, struct __bionic_zero_size_is_okay_t ok __attribute__((unused)))
-        __overloadable {
-    return __builtin___memset_chk(s, c, n, __bos0(s));
-}
-
-extern struct __bionic_zero_size_is_okay_t __bionic_zero_size_is_okay;
-/* We verify that `c` is non-zero, because as pointless as memset(foo, 0, 0) is,
- * flipping size + count will do nothing.
- */
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-void* memset(void* _Nonnull s, int c, size_t n) __overloadable
-        __enable_if(c && !n, "selected when we'll set zero bytes")
-        __RENAME_CLANG(memset)
-        __warnattr_real("will set 0 bytes; maybe the arguments got flipped? "
-                        "(Add __bionic_zero_size_is_okay as a fourth argument "
-                        "to silence this.)");
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#undef __error_zero_size
-#undef __error_if_overflows_dst
-#else // defined(__clang__)
-extern char* __strncpy_real(char* __restrict, const char*, size_t) __RENAME(strncpy);
-extern void* __memrchr_real(const void*, int, size_t) __RENAME(memrchr);
-extern size_t __strlcpy_real(char* __restrict, const char* __restrict, size_t)
-    __RENAME(strlcpy);
-extern size_t __strlcat_real(char* __restrict, const char* __restrict, size_t)
-    __RENAME(strlcat);
-
-__errordecl(__memchr_buf_size_error, "memchr called with size bigger than buffer");
-__errordecl(__memrchr_buf_size_error, "memrchr called with size bigger than buffer");
-
-#if __ANDROID_API__ >= __ANDROID_API_M__
-__BIONIC_FORTIFY_INLINE
-void* memchr(const void *_Nonnull s __pass_object_size, int c, size_t n) {
-    size_t bos = __bos(s);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin_memchr(s, c, n);
-    }
-
-    if (__builtin_constant_p(n) && (n > bos)) {
-        __memchr_buf_size_error();
-    }
-
-    if (__builtin_constant_p(n) && (n <= bos)) {
-        return __builtin_memchr(s, c, n);
-    }
-
-    return __memchr_chk(s, c, n, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-void* memrchr(const void* s, int c, size_t n) {
-    size_t bos = __bos(s);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __memrchr_real(s, c, n);
-    }
-
-    if (__builtin_constant_p(n) && (n > bos)) {
-        __memrchr_buf_size_error();
-    }
-
-    if (__builtin_constant_p(n) && (n <= bos)) {
-        return __memrchr_real(s, c, n);
-    }
-
-    return __memrchr_chk(s, c, n, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_L__
-__BIONIC_FORTIFY_INLINE
-char* stpncpy(char* _Nonnull __restrict dst, const char* _Nonnull __restrict src, size_t n) {
-    size_t bos_dst = __bos(dst);
-    size_t bos_src = __bos(src);
-
-    if (bos_src == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin___stpncpy_chk(dst, src, n, bos_dst);
-    }
-
-    if (__builtin_constant_p(n) && (n <= bos_src)) {
-        return __builtin___stpncpy_chk(dst, src, n, bos_dst);
-    }
-
-    size_t slen = __builtin_strlen(src);
-    if (__builtin_constant_p(slen)) {
-        return __builtin___stpncpy_chk(dst, src, n, bos_dst);
-    }
-
-    return __stpncpy_chk2(dst, src, n, bos_dst, bos_src);
-}
-
-__BIONIC_FORTIFY_INLINE
-char* strncpy(char* _Nonnull __restrict dst, const char* _Nonnull __restrict src, size_t n) {
-    size_t bos_dst = __bos(dst);
-    size_t bos_src = __bos(src);
-
-    if (bos_src == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __strncpy_real(dst, src, n);
-    }
-
-    if (__builtin_constant_p(n) && (n <= bos_src)) {
-        return __builtin___strncpy_chk(dst, src, n, bos_dst);
-    }
-
-    size_t slen = __builtin_strlen(src);
-    if (__builtin_constant_p(slen)) {
-        return __builtin___strncpy_chk(dst, src, n, bos_dst);
-    }
-
-    return __strncpy_chk2(dst, src, n, bos_dst, bos_src);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR1__
-__BIONIC_FORTIFY_INLINE
-size_t strlcpy(char* _Nonnull __restrict dst __pass_object_size, const char* _Nonnull __restrict src, size_t size) {
-    size_t bos = __bos(dst);
-
-    // Compiler doesn't know destination size. Don't call __strlcpy_chk
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __strlcpy_real(dst, src, size);
-    }
-
-    // Compiler can prove, at compile time, that the passed in size
-    // is always <= the actual object size. Don't call __strlcpy_chk
-    if (__builtin_constant_p(size) && (size <= bos)) {
-        return __strlcpy_real(dst, src, size);
-    }
-
-    return __strlcpy_chk(dst, src, size, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-size_t strlcat(char* _Nonnull __restrict dst, const char* _Nonnull __restrict src, size_t size) {
-    size_t bos = __bos(dst);
-
-    // Compiler doesn't know destination size. Don't call __strlcat_chk
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __strlcat_real(dst, src, size);
-    }
-
-    // Compiler can prove, at compile time, that the passed in size
-    // is always <= the actual object size. Don't call __strlcat_chk
-    if (__builtin_constant_p(size) && (size <= bos)) {
-        return __strlcat_real(dst, src, size);
-    }
-
-    return __strlcat_chk(dst, src, size, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-size_t strlen(const char* _Nonnull s) __overloadable {
-    size_t bos = __bos(s);
-
-    // Compiler doesn't know destination size. Don't call __strlen_chk
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin_strlen(s);
-    }
-
-    size_t slen = __builtin_strlen(s);
-    if (__builtin_constant_p(slen)) {
-        return slen;
-    }
-
-    return __strlen_chk(s, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
-
-#if  __ANDROID_API__ >= __ANDROID_API_J_MR2__
-__BIONIC_FORTIFY_INLINE
-char* strchr(const char* _Nonnull s, int c) {
-    size_t bos = __bos(s);
-
-    // Compiler doesn't know destination size. Don't call __strchr_chk
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin_strchr(s, c);
-    }
-
-    size_t slen = __builtin_strlen(s);
-    if (__builtin_constant_p(slen) && (slen < bos)) {
-        return __builtin_strchr(s, c);
-    }
-
-    return __strchr_chk(s, c, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-char* strrchr(const char* _Nonnull s, int c) {
-    size_t bos = __bos(s);
-
-    // Compiler doesn't know destination size. Don't call __strrchr_chk
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __builtin_strrchr(s, c);
-    }
-
-    size_t slen = __builtin_strlen(s);
-    if (__builtin_constant_p(slen) && (slen < bos)) {
-        return __builtin_strrchr(s, c);
-    }
-
-    return __strrchr_chk(s, c, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
-#endif /* defined(__clang__) */
-#endif /* defined(__BIONIC_FORTIFY) */
+#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
+#include <bits/fortify/string.h>
+#endif
 
 /* Const-correct overloads. Placed after FORTIFY so we call those functions, if possible. */
 #if defined(__cplusplus) && defined(__clang__)
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index dd5b345..9c662ba 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -185,11 +185,16 @@
 #  define __warnattr(msg) __attribute__((deprecated(msg)))
 #  define __warnattr_real(msg) __attribute__((deprecated(msg)))
 #  define __enable_if(cond, msg) __attribute__((enable_if(cond, msg)))
+#  define __clang_error_if(cond, msg) __attribute__((diagnose_if(cond, msg, "error")))
+#  define __clang_warning_if(cond, msg) __attribute__((diagnose_if(cond, msg, "warning")))
 #else
 #  define __errorattr(msg) __attribute__((__error__(msg)))
 #  define __warnattr(msg) __attribute__((__warning__(msg)))
 #  define __warnattr_real __warnattr
 /* enable_if doesn't exist on other compilers; give an error if it's used. */
+/* diagnose_if doesn't exist either, but it's often tagged on non-clang-specific functions */
+#  define __clang_error_if(cond, msg)
+#  define __clang_warning_if(cond, msg)
 
 /* errordecls really don't work as well in clang as they do in GCC. */
 #  define __errordecl(name, msg) extern void name(void) __errorattr(msg)
@@ -309,6 +314,11 @@
 #define __pass_object_size __pass_object_size_n(__bos_level)
 #define __pass_object_size0 __pass_object_size_n(0)
 
+/* FIXME: This should be __BIONIC_FORTIFY, but we don't enable FORTIFY in -O0. */
+#if (defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0) || defined(__BIONIC_DECLARE_FORTIFY_HELPERS)
+#  define __BIONIC_INCLUDE_FORTIFY_HEADERS 1
+#endif
+
 /*
  * Used to support clangisms with FORTIFY. Because these change how symbols are
  * emitted, we need to ensure that bionic itself is built fortified. But lots
diff --git a/libc/include/sys/socket.h b/libc/include/sys/socket.h
index 2dc54aa..6875d7f 100644
--- a/libc/include/sys/socket.h
+++ b/libc/include/sys/socket.h
@@ -325,140 +325,9 @@
 __socketcall ssize_t recvfrom(int, void*, size_t, int, struct sockaddr*,
         socklen_t*) __overloadable __RENAME_CLANG(recvfrom);
 
-extern ssize_t __sendto_chk(int, const void*, size_t, size_t, int, const struct sockaddr*,
-        socklen_t) __INTRODUCED_IN(26);
-ssize_t __recvfrom_chk(int, void*, size_t, size_t, int, struct sockaddr*,
-        socklen_t*) __INTRODUCED_IN(21);
-
-#if defined(__BIONIC_FORTIFY)
-
-#define __recvfrom_bad_size "recvfrom called with size bigger than buffer"
-#define __sendto_bad_size "sendto called with size bigger than buffer"
-#if defined(__clang__)
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t recvfrom(int fd, void* const buf __pass_object_size0, size_t len,
-                 int flags, struct sockaddr* src_addr, socklen_t* addr_len)
-        __overloadable
-        __enable_if(__bos(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                    __bos(buf) < len, "selected when the buffer is too small")
-        __errorattr(__recvfrom_bad_size);
-
-__BIONIC_FORTIFY_INLINE
-ssize_t recvfrom(int fd, void* const buf __pass_object_size0, size_t len,
-                 int flags, struct sockaddr* src_addr, socklen_t* addr_len)
-      __overloadable {
-  size_t bos = __bos0(buf);
-
-  if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-    return __call_bypassing_fortify(recvfrom)(fd, buf, len, flags, src_addr,
-              addr_len);
-  }
-
-  return __recvfrom_chk(fd, buf, len, bos, flags, src_addr, addr_len);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_N_MR1__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t sendto(int fd, const void* buf, size_t len, int flags,
-               const struct sockaddr* dest_addr, socklen_t addr_len)
-        __overloadable
-        __enable_if(__bos0(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                    __bos0(buf) < len, "selected when the buffer is too small")
-        __errorattr(__sendto_bad_size);
-
-__BIONIC_FORTIFY_INLINE
-ssize_t sendto(int fd, const void* const buf __pass_object_size0, size_t len,
-               int flags, const struct sockaddr* dest_addr, socklen_t addr_len)
-      __overloadable {
-  size_t bos = __bos0(buf);
-
-  if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-    return __call_bypassing_fortify(sendto)(fd, buf, len, flags, dest_addr,
-              addr_len);
-  }
-
-  return __sendto_chk(fd, buf, len, bos, flags, dest_addr, addr_len);
-}
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t send(int socket, const void* buf, size_t len, int flags)
-        __overloadable
-        __enable_if(__bos0(buf) != __BIONIC_FORTIFY_UNKNOWN_SIZE &&
-                    __bos0(buf) < len, "selected when the buffer is too small")
-        __errorattr("send called with size bigger than buffer");
-#endif /* __ANDROID_API__ >= __ANDROID_API_N_MR1__ */
-
-#else /* defined(__clang__) */
-ssize_t __recvfrom_real(int, void*, size_t, int, struct sockaddr*, socklen_t*) __RENAME(recvfrom);
-__errordecl(__recvfrom_error, __recvfrom_bad_size);
-
-extern ssize_t __sendto_real(int, const void*, size_t, int, const struct sockaddr*, socklen_t)
-        __RENAME(sendto);
-__errordecl(__sendto_error, __sendto_bad_size);
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_FORTIFY_INLINE
-ssize_t recvfrom(int fd, void* buf, size_t len, int flags,
-                 struct sockaddr* src_addr, socklen_t* addr_len) {
-  size_t bos = __bos0(buf);
-
-  if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-    return __recvfrom_real(fd, buf, len, flags, src_addr, addr_len);
-  }
-
-  if (__builtin_constant_p(len) && (len <= bos)) {
-    return __recvfrom_real(fd, buf, len, flags, src_addr, addr_len);
-  }
-
-  if (__builtin_constant_p(len) && (len > bos)) {
-    __recvfrom_error();
-  }
-
-  return __recvfrom_chk(fd, buf, len, bos, flags, src_addr, addr_len);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_N_MR1__
-__BIONIC_FORTIFY_INLINE
-ssize_t sendto(int fd, const void* buf, size_t len, int flags,
-               const struct sockaddr* dest_addr, socklen_t addr_len) {
-  size_t bos = __bos0(buf);
-
-  if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-    return __sendto_real(fd, buf, len, flags, dest_addr, addr_len);
-  }
-
-  if (__builtin_constant_p(len) && (len <= bos)) {
-    return __sendto_real(fd, buf, len, flags, dest_addr, addr_len);
-  }
-
-  if (__builtin_constant_p(len) && (len > bos)) {
-    __sendto_error();
-  }
-
-  return __sendto_chk(fd, buf, len, bos, flags, dest_addr, addr_len);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N_MR1__ */
-
-#endif /* defined(__clang__) */
-#undef __recvfrom_bad_size
-#undef __sendto_bad_size
-
-__BIONIC_FORTIFY_INLINE
-ssize_t recv(int socket, void* const buf __pass_object_size0, size_t len,
-             int flags) __overloadable {
-  return recvfrom(socket, buf, len, flags, NULL, 0);
-}
-
-__BIONIC_FORTIFY_INLINE
-ssize_t send(int socket, const void* const buf __pass_object_size0, size_t len, int flags)
-        __overloadable {
-  return sendto(socket, buf, len, flags, NULL, 0);
-}
-
-#endif /* __BIONIC_FORTIFY */
+#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
+#include <bits/fortify/socket.h>
+#endif
 
 #undef __socketcall
 
diff --git a/libc/include/sys/stat.h b/libc/include/sys/stat.h
index 47ff5c4..b8e3cb1 100644
--- a/libc/include/sys/stat.h
+++ b/libc/include/sys/stat.h
@@ -167,51 +167,9 @@
 int mknod(const char*, mode_t, dev_t);
 mode_t umask(mode_t) __overloadable __RENAME_CLANG(umask);
 
-mode_t __umask_chk(mode_t) __INTRODUCED_IN(18);
-
-#if defined(__BIONIC_FORTIFY)
-#define __umask_invalid_mode_str "umask called with invalid mode"
-
-#if defined(__clang__)
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR2__
-/*
- * Abuse enable_if to make these be seen as overloads of umask, rather than
- * definitions.
- */
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-mode_t umask(mode_t mode) __overloadable
-        __enable_if(1, "")
-        __enable_if(mode & ~0777, __umask_invalid_mode_str)
-        __errorattr(__umask_invalid_mode_str);
-
-__BIONIC_FORTIFY_INLINE
-mode_t umask(mode_t mode) __enable_if(1, "") __overloadable {
-  return __umask_chk(mode);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
-
-#else /* defined(__clang__) */
-__errordecl(__umask_invalid_mode, __umask_invalid_mode_str);
-extern mode_t __umask_real(mode_t) __RENAME(umask);
-
-#if __ANDROID_API__ >= __ANDROID_API_J_MR2__
-__BIONIC_FORTIFY_INLINE
-mode_t umask(mode_t mode) {
-  if (__builtin_constant_p(mode)) {
-    if ((mode & 0777) != mode) {
-      __umask_invalid_mode();
-    }
-    return __umask_real(mode);
-  }
-  return __umask_chk(mode);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_J_MR2__ */
-
-#endif /* defined(__clang__) */
-#undef __umask_invalid_mode_str
-
-#endif /* defined(__BIONIC_FORTIFY) */
+#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
+#include <bits/fortify/stat.h>
+#endif
 
 #if __ANDROID_API__ >= __ANDROID_API_L__
 int mkfifo(const char*, mode_t) __INTRODUCED_IN(21);
diff --git a/libc/include/sys/statvfs.h b/libc/include/sys/statvfs.h
index af1b9c0..5df4160 100644
--- a/libc/include/sys/statvfs.h
+++ b/libc/include/sys/statvfs.h
@@ -59,10 +59,8 @@
 #define ST_NODIRATIME  0x0800
 #define ST_RELATIME    0x1000
 
-int statvfs(const char* __restrict _Nonnull, struct statvfs* __restrict _Nonnull)
-  __INTRODUCED_IN(19);
-int statvfs64(const char* __restrict _Nonnull, struct statvfs64* __restrict _Nonnull)
-  __INTRODUCED_IN(21);
+int statvfs(const char* _Nonnull, struct statvfs* _Nonnull) __INTRODUCED_IN(19);
+int statvfs64(const char* _Nonnull, struct statvfs64* _Nonnull) __INTRODUCED_IN(21);
 int fstatvfs(int, struct statvfs* _Nonnull) __INTRODUCED_IN(19);
 int fstatvfs64(int, struct statvfs64* _Nonnull) __INTRODUCED_IN(21);
 
diff --git a/libc/include/uchar.h b/libc/include/uchar.h
index 818acb1..ac0cf1d 100644
--- a/libc/include/uchar.h
+++ b/libc/include/uchar.h
@@ -43,12 +43,10 @@
 #define __STD_UTF_16__ 1
 #define __STD_UTF_32__ 1
 
-size_t c16rtomb(char* __restrict, char16_t, mbstate_t* __restrict) __INTRODUCED_IN(21);
-size_t c32rtomb(char* __restrict, char32_t, mbstate_t* __restrict) __INTRODUCED_IN(21);
-size_t mbrtoc16(char16_t* __restrict, const char* __restrict, size_t, mbstate_t* __restrict)
-  __INTRODUCED_IN(21);
-size_t mbrtoc32(char32_t* __restrict, const char* __restrict, size_t, mbstate_t* __restrict)
-  __INTRODUCED_IN(21);
+size_t c16rtomb(char*, char16_t, mbstate_t*) __INTRODUCED_IN(21);
+size_t c32rtomb(char*, char32_t, mbstate_t*) __INTRODUCED_IN(21);
+size_t mbrtoc16(char16_t*, const char*, size_t, mbstate_t*) __INTRODUCED_IN(21);
+size_t mbrtoc32(char32_t*, const char*, size_t, mbstate_t*) __INTRODUCED_IN(21);
 
 __END_DECLS
 
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 8336976..ff77421 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -242,505 +242,13 @@
     } while (_rc == -1 && errno == EINTR); \
     _rc; })
 
-/* TODO(unified-headers): Factor out all the FORTIFY features. */
-char* __getcwd_chk(char*, size_t, size_t) __INTRODUCED_IN(24);
-
-ssize_t __pread_chk(int, void*, size_t, off_t, size_t) __INTRODUCED_IN(23);
-ssize_t __pread_real(int, void*, size_t, off_t) __RENAME(pread);
-
-ssize_t __pread64_chk(int, void*, size_t, off64_t, size_t) __INTRODUCED_IN(23);
-ssize_t __pread64_real(int, void*, size_t, off64_t) __RENAME(pread64) __INTRODUCED_IN(12);
-
-ssize_t __pwrite_chk(int, const void*, size_t, off_t, size_t) __INTRODUCED_IN(24);
-ssize_t __pwrite_real(int, const void*, size_t, off_t) __RENAME(pwrite);
-
-ssize_t __pwrite64_chk(int, const void*, size_t, off64_t, size_t) __INTRODUCED_IN(24);
-ssize_t __pwrite64_real(int, const void*, size_t, off64_t) __RENAME(pwrite64)
-  __INTRODUCED_IN(12);
-
-ssize_t __read_chk(int, void*, size_t, size_t) __INTRODUCED_IN(21);
-ssize_t __write_chk(int, const void*, size_t, size_t) __INTRODUCED_IN(24);
-ssize_t __readlink_chk(const char*, char*, size_t, size_t) __INTRODUCED_IN(23);
-ssize_t __readlinkat_chk(int dirfd, const char*, char*, size_t, size_t) __INTRODUCED_IN(23);
-
 int getdomainname(char*, size_t) __INTRODUCED_IN(26);
 int setdomainname(const char*, size_t) __INTRODUCED_IN(26);
 
-#if defined(__BIONIC_FORTIFY)
-
-#if defined(__USE_FILE_OFFSET64)
-#define __PREAD_PREFIX(x) __pread64_ ## x
-#define __PWRITE_PREFIX(x) __pwrite64_ ## x
-#else
-#define __PREAD_PREFIX(x) __pread_ ## x
-#define __PWRITE_PREFIX(x) __pwrite_ ## x
+#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
+#include <bits/fortify/unistd.h>
 #endif
 
-#if defined(__clang__)
-#define __error_if_overflows_ssizet(what) \
-    __enable_if(what > SSIZE_MAX, #what " must be <= SSIZE_MAX") \
-    __errorattr(#what " must be <= SSIZE_MAX")
-
-#define __enable_if_no_overflow_ssizet(what) \
-    __enable_if((what) <= SSIZE_MAX, "enabled if " #what " <= SSIZE_MAX")
-
-#define __error_if_overflows_objectsize(what, objsize) \
-    __enable_if((objsize) != __BIONIC_FORTIFY_UNKNOWN_SIZE && \
-                    (what) > (objsize), \
-                "'" #what "' bytes overflows the given object") \
-    __errorattr("'" #what "' bytes overflows the given object")
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-char* getcwd(char* buf, size_t size) __overloadable
-        __error_if_overflows_objectsize(size, __bos(buf));
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_FORTIFY_INLINE
-char* getcwd(char* const __pass_object_size buf, size_t size) __overloadable {
-    size_t bos = __bos(buf);
-
-    /*
-     * Clang responds bos==0 if buf==NULL
-     * (https://llvm.org/bugs/show_bug.cgi?id=23277). Given that NULL is a valid
-     * value, we need to handle that.
-     */
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE || buf == NULL) {
-        return __call_bypassing_fortify(getcwd)(buf, size);
-    }
-
-    return __getcwd_chk(buf, size, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_M__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t pread(int fd, void* buf, size_t count, off_t offset) __overloadable
-        __error_if_overflows_ssizet(count);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t pread(int fd, void* buf, size_t count, off_t offset) __overloadable
-        __enable_if_no_overflow_ssizet(count)
-        __error_if_overflows_objectsize(count, __bos0(buf));
-
-__BIONIC_FORTIFY_INLINE
-ssize_t pread(int fd, void* const __pass_object_size0 buf, size_t count,
-              off_t offset) __overloadable {
-    size_t bos = __bos0(buf);
-
-    if (count == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __PREAD_PREFIX(real)(fd, buf, count, offset);
-    }
-
-    return __PREAD_PREFIX(chk)(fd, buf, count, offset, bos);
-}
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t pread64(int fd, void* buf, size_t count, off64_t offset) __overloadable
-        __error_if_overflows_ssizet(count);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t pread64(int fd, void* buf, size_t count, off64_t offset) __overloadable
-        __enable_if_no_overflow_ssizet(count)
-        __error_if_overflows_objectsize(count, __bos0(buf));
-
-__BIONIC_FORTIFY_INLINE
-ssize_t pread64(int fd, void* const __pass_object_size0 buf, size_t count,
-                off64_t offset) __overloadable {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __pread64_real(fd, buf, count, offset);
-    }
-
-    return __pread64_chk(fd, buf, count, offset, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t pwrite(int fd, const void* buf, size_t count, off_t offset)
-        __overloadable
-        __error_if_overflows_ssizet(count);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t pwrite(int fd, const void* buf, size_t count, off_t offset)
-        __overloadable
-        __enable_if_no_overflow_ssizet(count)
-        __error_if_overflows_objectsize(count, __bos0(buf));
-
-__BIONIC_FORTIFY_INLINE
-ssize_t pwrite(int fd, const void* const __pass_object_size0 buf, size_t count,
-               off_t offset) __overloadable {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __PWRITE_PREFIX(real)(fd, buf, count, offset);
-    }
-
-    return __PWRITE_PREFIX(chk)(fd, buf, count, offset, bos);
-}
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t pwrite64(int fd, const void* buf, size_t count, off64_t offset)
-        __overloadable
-        __error_if_overflows_ssizet(count);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t pwrite64(int fd, const void* buf, size_t count, off64_t offset)
-        __overloadable
-        __enable_if_no_overflow_ssizet(count)
-        __error_if_overflows_objectsize(count, __bos0(buf));
-
-__BIONIC_FORTIFY_INLINE
-ssize_t pwrite64(int fd, const void* const __pass_object_size0 buf,
-                 size_t count, off64_t offset) __overloadable {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __pwrite64_real(fd, buf, count, offset);
-    }
-
-    return __pwrite64_chk(fd, buf, count, offset, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_L__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t read(int fd, void* buf, size_t count) __overloadable
-        __error_if_overflows_ssizet(count);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t read(int fd, void* buf, size_t count) __overloadable
-        __enable_if_no_overflow_ssizet(count)
-        __error_if_overflows_objectsize(count, __bos0(buf));
-
-__BIONIC_FORTIFY_INLINE
-ssize_t read(int fd, void* const __pass_object_size0 buf, size_t count)
-        __overloadable {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(read)(fd, buf, count);
-    }
-
-    return __read_chk(fd, buf, count, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t write(int fd, const void* buf, size_t count) __overloadable
-        __error_if_overflows_ssizet(count);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t write(int fd, const void* buf, size_t count) __overloadable
-        __enable_if_no_overflow_ssizet(count)
-        __error_if_overflows_objectsize(count, __bos0(buf));
-
-__BIONIC_FORTIFY_INLINE
-ssize_t write(int fd, const void* const __pass_object_size0 buf, size_t count)
-        __overloadable {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(write)(fd, buf, count);
-    }
-
-    return __write_chk(fd, buf, count, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_M__
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t readlink(const char* path, char* buf, size_t size) __overloadable
-        __error_if_overflows_ssizet(size);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t readlink(const char* path, char* buf, size_t size) __overloadable
-        __enable_if_no_overflow_ssizet(size)
-        __error_if_overflows_objectsize(size, __bos(buf));
-
-__BIONIC_FORTIFY_INLINE
-ssize_t readlink(const char* path, char* const __pass_object_size buf,
-                 size_t size) __overloadable {
-    size_t bos = __bos(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(readlink)(path, buf, size);
-    }
-
-    return __readlink_chk(path, buf, size, bos);
-}
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t readlinkat(int dirfd, const char* path, char* buf, size_t size)
-        __overloadable
-        __error_if_overflows_ssizet(size);
-
-__BIONIC_ERROR_FUNCTION_VISIBILITY
-ssize_t readlinkat(int dirfd, const char* path, char* buf, size_t size)
-        __overloadable
-        __enable_if_no_overflow_ssizet(size)
-        __error_if_overflows_objectsize(size, __bos(buf));
-
-__BIONIC_FORTIFY_INLINE
-ssize_t readlinkat(int dirfd, const char* path,
-                   char* const __pass_object_size buf, size_t size)
-        __overloadable {
-    size_t bos = __bos(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __call_bypassing_fortify(readlinkat)(dirfd, path, buf, size);
-    }
-
-    return __readlinkat_chk(dirfd, path, buf, size, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
-
-#undef __enable_if_no_overflow_ssizet
-#undef __error_if_overflows_objectsize
-#undef __error_if_overflows_ssizet
-#else /* defined(__clang__) */
-
-char* __getcwd_real(char*, size_t) __RENAME(getcwd);
-ssize_t __read_real(int, void*, size_t) __RENAME(read);
-ssize_t __write_real(int, const void*, size_t) __RENAME(write);
-ssize_t __readlink_real(const char*, char*, size_t) __RENAME(readlink);
-ssize_t __readlinkat_real(int dirfd, const char*, char*, size_t) __RENAME(readlinkat);
-
-__errordecl(__getcwd_dest_size_error, "getcwd called with size bigger than destination");
-__errordecl(__pread_dest_size_error, "pread called with size bigger than destination");
-__errordecl(__pread_count_toobig_error, "pread called with count > SSIZE_MAX");
-__errordecl(__pread64_dest_size_error, "pread64 called with size bigger than destination");
-__errordecl(__pread64_count_toobig_error, "pread64 called with count > SSIZE_MAX");
-__errordecl(__pwrite_dest_size_error, "pwrite called with size bigger than destination");
-__errordecl(__pwrite_count_toobig_error, "pwrite called with count > SSIZE_MAX");
-__errordecl(__pwrite64_dest_size_error, "pwrite64 called with size bigger than destination");
-__errordecl(__pwrite64_count_toobig_error, "pwrite64 called with count > SSIZE_MAX");
-__errordecl(__read_dest_size_error, "read called with size bigger than destination");
-__errordecl(__read_count_toobig_error, "read called with count > SSIZE_MAX");
-__errordecl(__write_dest_size_error, "write called with size bigger than destination");
-__errordecl(__write_count_toobig_error, "write called with count > SSIZE_MAX");
-__errordecl(__readlink_dest_size_error, "readlink called with size bigger than destination");
-__errordecl(__readlink_size_toobig_error, "readlink called with size > SSIZE_MAX");
-__errordecl(__readlinkat_dest_size_error, "readlinkat called with size bigger than destination");
-__errordecl(__readlinkat_size_toobig_error, "readlinkat called with size > SSIZE_MAX");
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_FORTIFY_INLINE
-char* getcwd(char* buf, size_t size) __overloadable {
-    size_t bos = __bos(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __getcwd_real(buf, size);
-    }
-
-    if (__builtin_constant_p(size) && (size > bos)) {
-        __getcwd_dest_size_error();
-    }
-
-    if (__builtin_constant_p(size) && (size <= bos)) {
-        return __getcwd_real(buf, size);
-    }
-
-    return __getcwd_chk(buf, size, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_M__
-__BIONIC_FORTIFY_INLINE
-ssize_t pread(int fd, void* buf, size_t count, off_t offset) {
-    size_t bos = __bos0(buf);
-
-    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
-        __PREAD_PREFIX(count_toobig_error)();
-    }
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __PREAD_PREFIX(real)(fd, buf, count, offset);
-    }
-
-    if (__builtin_constant_p(count) && (count > bos)) {
-        __PREAD_PREFIX(dest_size_error)();
-    }
-
-    if (__builtin_constant_p(count) && (count <= bos)) {
-        return __PREAD_PREFIX(real)(fd, buf, count, offset);
-    }
-
-    return __PREAD_PREFIX(chk)(fd, buf, count, offset, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-ssize_t pread64(int fd, void* buf, size_t count, off64_t offset) {
-    size_t bos = __bos0(buf);
-
-    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
-        __pread64_count_toobig_error();
-    }
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __pread64_real(fd, buf, count, offset);
-    }
-
-    if (__builtin_constant_p(count) && (count > bos)) {
-        __pread64_dest_size_error();
-    }
-
-    if (__builtin_constant_p(count) && (count <= bos)) {
-        return __pread64_real(fd, buf, count, offset);
-    }
-
-    return __pread64_chk(fd, buf, count, offset, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_FORTIFY_INLINE
-ssize_t pwrite(int fd, const void* buf, size_t count, off_t offset) {
-    size_t bos = __bos0(buf);
-
-    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
-        __PWRITE_PREFIX(count_toobig_error)();
-    }
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __PWRITE_PREFIX(real)(fd, buf, count, offset);
-    }
-
-    if (__builtin_constant_p(count) && (count > bos)) {
-        __PWRITE_PREFIX(dest_size_error)();
-    }
-
-    if (__builtin_constant_p(count) && (count <= bos)) {
-        return __PWRITE_PREFIX(real)(fd, buf, count, offset);
-    }
-
-    return __PWRITE_PREFIX(chk)(fd, buf, count, offset, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-ssize_t pwrite64(int fd, const void* buf, size_t count, off64_t offset) {
-    size_t bos = __bos0(buf);
-
-    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
-        __pwrite64_count_toobig_error();
-    }
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __pwrite64_real(fd, buf, count, offset);
-    }
-
-    if (__builtin_constant_p(count) && (count > bos)) {
-        __pwrite64_dest_size_error();
-    }
-
-    if (__builtin_constant_p(count) && (count <= bos)) {
-        return __pwrite64_real(fd, buf, count, offset);
-    }
-
-    return __pwrite64_chk(fd, buf, count, offset, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_L__
-__BIONIC_FORTIFY_INLINE
-ssize_t read(int fd, void* buf, size_t count) {
-    size_t bos = __bos0(buf);
-
-    if (__builtin_constant_p(count) && (count > SSIZE_MAX)) {
-        __read_count_toobig_error();
-    }
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __read_real(fd, buf, count);
-    }
-
-    if (__builtin_constant_p(count) && (count > bos)) {
-        __read_dest_size_error();
-    }
-
-    if (__builtin_constant_p(count) && (count <= bos)) {
-        return __read_real(fd, buf, count);
-    }
-
-    return __read_chk(fd, buf, count, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_N__
-__BIONIC_FORTIFY_INLINE
-ssize_t write(int fd, const void* buf, size_t count) {
-    size_t bos = __bos0(buf);
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __write_real(fd, buf, count);
-    }
-
-    if (__builtin_constant_p(count) && (count > bos)) {
-        __write_dest_size_error();
-    }
-
-    if (__builtin_constant_p(count) && (count <= bos)) {
-        return __write_real(fd, buf, count);
-    }
-
-    return __write_chk(fd, buf, count, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_N__ */
-
-#if __ANDROID_API__ >= __ANDROID_API_M__
-__BIONIC_FORTIFY_INLINE
-ssize_t readlink(const char* path, char* buf, size_t size) {
-    size_t bos = __bos(buf);
-
-    if (__builtin_constant_p(size) && (size > SSIZE_MAX)) {
-        __readlink_size_toobig_error();
-    }
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __readlink_real(path, buf, size);
-    }
-
-    if (__builtin_constant_p(size) && (size > bos)) {
-        __readlink_dest_size_error();
-    }
-
-    if (__builtin_constant_p(size) && (size <= bos)) {
-        return __readlink_real(path, buf, size);
-    }
-
-    return __readlink_chk(path, buf, size, bos);
-}
-
-__BIONIC_FORTIFY_INLINE
-ssize_t readlinkat(int dirfd, const char* path, char* buf, size_t size) {
-    size_t bos = __bos(buf);
-
-    if (__builtin_constant_p(size) && (size > SSIZE_MAX)) {
-        __readlinkat_size_toobig_error();
-    }
-
-    if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
-        return __readlinkat_real(dirfd, path, buf, size);
-    }
-
-    if (__builtin_constant_p(size) && (size > bos)) {
-        __readlinkat_dest_size_error();
-    }
-
-    if (__builtin_constant_p(size) && (size <= bos)) {
-        return __readlinkat_real(dirfd, path, buf, size);
-    }
-
-    return __readlinkat_chk(dirfd, path, buf, size, bos);
-}
-#endif /* __ANDROID_API__ >= __ANDROID_API_M__ */
-#endif /* defined(__clang__) */
-#undef __PREAD_PREFIX
-#undef __PWRITE_PREFIX
-#endif /* defined(__BIONIC_FORTIFY) */
-
 __END_DECLS
 
 #endif /* _UNISTD_H_ */
diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index afb02ca..1697116 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -202,9 +202,9 @@
 wint_t __fgetwc_unlock(FILE *);
 wint_t	__ungetwc(wint_t, FILE *);
 int	__vfprintf(FILE *, const char *, __va_list);
-int	__svfscanf(FILE * __restrict, const char * __restrict, __va_list);
-int	__vfwprintf(FILE * __restrict, const wchar_t * __restrict, __va_list);
-int	__vfwscanf(FILE * __restrict, const wchar_t * __restrict, __va_list);
+int	__svfscanf(FILE *, const char *, __va_list);
+int	__vfwprintf(FILE *, const wchar_t *, __va_list);
+int	__vfwscanf(FILE *, const wchar_t *, __va_list);
 
 /*
  * Return true if the given FILE cannot be written now.
diff --git a/tools/versioner/src/Utils.cpp b/tools/versioner/src/Utils.cpp
index ef7facc..ca186a4 100644
--- a/tools/versioner/src/Utils.cpp
+++ b/tools/versioner/src/Utils.cpp
@@ -37,7 +37,8 @@
   return buf;
 }
 
-std::vector<std::string> collectHeaders(const std::string& directory) {
+std::vector<std::string> collectHeaders(const std::string& directory,
+                                        const std::unordered_set<std::string>& ignored_directories) {
   std::vector<std::string> headers;
 
   char* dir_argv[2] = { const_cast<char*>(directory.c_str()), nullptr };
@@ -48,16 +49,34 @@
     err(1, "failed to open directory '%s'", directory.c_str());
   }
 
+  FTSENT* skipping = nullptr;
   while (FTSENT* ent = fts_read(fts.get())) {
-    if (ent->fts_info & (FTS_D | FTS_DP)) {
+    if (ent->fts_info & FTS_DP) {
+      if (ent == skipping) {
+        skipping = nullptr;
+      }
       continue;
     }
 
-    if (!android::base::EndsWith(ent->fts_path, ".h")) {
+    if (skipping != nullptr) {
       continue;
     }
 
-    headers.push_back(ent->fts_path);
+    if (ent->fts_info & FTS_D) {
+      if (ignored_directories.count(ent->fts_path) != 0) {
+        // fts_read guarantees that `ent` is valid and sane to hold on to until
+        // after it's returned with FTS_DP set.
+        skipping = ent;
+      }
+      continue;
+    }
+
+    std::string path = ent->fts_path;
+    if (!android::base::EndsWith(path, ".h")) {
+      continue;
+    }
+
+    headers.push_back(std::move(path));
   }
 
   return headers;
diff --git a/tools/versioner/src/Utils.h b/tools/versioner/src/Utils.h
index 44a34f8..9b45dcd 100644
--- a/tools/versioner/src/Utils.h
+++ b/tools/versioner/src/Utils.h
@@ -22,12 +22,14 @@
 #include <unistd.h>
 
 #include <string>
+#include <unordered_set>
 #include <vector>
 
 #include <llvm/ADT/StringRef.h>
 
 std::string getWorkingDir();
-std::vector<std::string> collectHeaders(const std::string& directory);
+std::vector<std::string> collectHeaders(const std::string& directory,
+                                        const std::unordered_set<std::string>& ignored_directories);
 
 static inline std::string dirname(const std::string& path) {
   std::unique_ptr<char, decltype(&free)> path_copy(strdup(path.c_str()), free);
diff --git a/tools/versioner/src/versioner.cpp b/tools/versioner/src/versioner.cpp
index 747c767..8db75d7 100644
--- a/tools/versioner/src/versioner.cpp
+++ b/tools/versioner/src/versioner.cpp
@@ -45,6 +45,7 @@
 #include <android-base/file.h>
 #include <android-base/macros.h>
 #include <android-base/parseint.h>
+#include <android-base/strings.h>
 
 #include "Arch.h"
 #include "DeclarationDatabase.h"
@@ -79,11 +80,21 @@
 #endif
 }
 
-static CompilationRequirements collectRequirements(const Arch& arch, const std::string& header_dir,
-                                                   const std::string& dependency_dir) {
-  std::vector<std::string> headers = collectHeaders(header_dir);
-  std::vector<std::string> dependencies = { header_dir };
-  if (!dependency_dir.empty()) {
+namespace {
+struct HeaderLocationInformation {
+  std::string header_dir;
+  std::string dependency_dir;
+  // Absolute paths to ignore all children -- including subdirectories -- of.
+  std::unordered_set<std::string> ignored_directories;
+};
+}
+
+static CompilationRequirements collectRequirements(const Arch& arch,
+                                                   const HeaderLocationInformation& location) {
+  std::vector<std::string> headers =
+      collectHeaders(location.header_dir, location.ignored_directories);
+  std::vector<std::string> dependencies = { location.header_dir };
+  if (!location.dependency_dir.empty()) {
     auto collect_children = [&dependencies](const std::string& dir_path) {
       DIR* dir = opendir(dir_path.c_str());
       if (!dir) {
@@ -114,8 +125,8 @@
       closedir(dir);
     };
 
-    collect_children(dependency_dir + "/common");
-    collect_children(dependency_dir + "/" + to_string(arch));
+    collect_children(location.dependency_dir + "/common");
+    collect_children(location.dependency_dir + "/" + to_string(arch));
   }
 
   auto new_end = std::remove_if(headers.begin(), headers.end(), [&arch](llvm::StringRef header) {
@@ -159,13 +170,12 @@
 }
 
 static std::unique_ptr<HeaderDatabase> compileHeaders(const std::set<CompilationType>& types,
-                                                      const std::string& header_dir,
-                                                      const std::string& dependency_dir) {
+                                                      const HeaderLocationInformation& location) {
   if (types.empty()) {
     errx(1, "compileHeaders received no CompilationTypes");
   }
 
-  auto vfs = createCommonVFS(header_dir, dependency_dir, add_include);
+  auto vfs = createCommonVFS(location.header_dir, location.dependency_dir, add_include);
 
   size_t thread_count = max_thread_count;
   std::vector<std::thread> threads;
@@ -176,7 +186,7 @@
   auto result = std::make_unique<HeaderDatabase>();
   for (const auto& type : types) {
     if (requirements.count(type.arch) == 0) {
-      requirements[type.arch] = collectRequirements(type.arch, header_dir, dependency_dir);
+      requirements[type.arch] = collectRequirements(type.arch, location);
     }
   }
 
@@ -454,6 +464,7 @@
     fprintf(stderr, "  -f\t\tpreprocess header files even if validation fails\n");
     fprintf(stderr, "\n");
     fprintf(stderr, "Miscellaneous:\n");
+    fprintf(stderr, "  -F\t\tdo not ignore FORTIFY headers by default\n");
     fprintf(stderr, "  -d\t\tdump function availability\n");
     fprintf(stderr, "  -j THREADS\tmaximum number of threads to use\n");
     fprintf(stderr, "  -v\t\tenable verbose logging\n");
@@ -477,9 +488,10 @@
   std::string preprocessor_output_path;
   bool force = false;
   bool dump = false;
+  bool ignore_fortify_headers = true;
 
   int c;
-  while ((c = getopt(argc, argv, "a:r:p:so:fdj:vhi")) != -1) {
+  while ((c = getopt(argc, argv, "a:r:p:so:fdj:vhFi")) != -1) {
     default_args = false;
     switch (c) {
       case 'a': {
@@ -565,6 +577,10 @@
         add_include = true;
         break;
 
+      case 'F':
+        ignore_fortify_headers = false;
+        break;
+
       default:
         usage();
         break;
@@ -575,8 +591,7 @@
     usage();
   }
 
-  std::string header_dir;
-  std::string dependency_dir;
+  HeaderLocationInformation location;
 
   const char* top = getenv("ANDROID_BUILD_TOP");
   if (!top && (optind == argc || add_include)) {
@@ -587,21 +602,32 @@
   if (optind == argc) {
     // Neither HEADER_PATH nor DEPS_PATH were specified, so try to figure them out.
     std::string versioner_dir = to_string(top) + "/bionic/tools/versioner";
-    header_dir = versioner_dir + "/current";
-    dependency_dir = versioner_dir + "/dependencies";
+    location.header_dir = versioner_dir + "/current";
+    location.dependency_dir = versioner_dir + "/dependencies";
     if (platform_dir.empty()) {
       platform_dir = versioner_dir + "/platforms";
     }
   } else {
-    if (!android::base::Realpath(argv[optind], &header_dir)) {
+    if (!android::base::Realpath(argv[optind], &location.header_dir)) {
       err(1, "failed to get realpath for path '%s'", argv[optind]);
     }
 
     if (argc - optind == 2) {
-      dependency_dir = argv[optind + 1];
+      location.dependency_dir = argv[optind + 1];
     }
   }
 
+  // Every file that lives in bits/fortify is logically a part of a header outside of bits/fortify.
+  // This makes the files there impossible to build on their own.
+  if (ignore_fortify_headers) {
+    std::string fortify_path = location.header_dir;
+    if (!android::base::EndsWith(location.header_dir, "/")) {
+      fortify_path += '/';
+    }
+    fortify_path += "bits/fortify";
+    location.ignored_directories.insert(std::move(fortify_path));
+  }
+
   if (selected_levels.empty()) {
     selected_levels = supported_levels;
   }
@@ -612,10 +638,10 @@
 
 
   struct stat st;
-  if (stat(header_dir.c_str(), &st) != 0) {
-    err(1, "failed to stat '%s'", header_dir.c_str());
+  if (const char *dir = location.header_dir.c_str(); stat(dir, &st) != 0) {
+    err(1, "failed to stat '%s'", dir);
   } else if (!S_ISDIR(st.st_mode)) {
-    errx(1, "'%s' is not a directory", header_dir.c_str());
+    errx(1, "'%s' is not a directory", dir);
   }
 
   std::set<CompilationType> compilation_types;
@@ -631,7 +657,7 @@
 
   auto start = std::chrono::high_resolution_clock::now();
   std::unique_ptr<HeaderDatabase> declaration_database =
-      compileHeaders(compilation_types, header_dir, dependency_dir);
+      compileHeaders(compilation_types, location);
   auto end = std::chrono::high_resolution_clock::now();
 
   if (verbose) {
@@ -641,7 +667,7 @@
 
   bool failed = false;
   if (dump) {
-    declaration_database->dump(header_dir + "/");
+    declaration_database->dump(location.header_dir + "/");
   } else {
     if (!sanityCheck(declaration_database.get())) {
       printf("versioner: sanity check failed\n");
@@ -657,7 +683,7 @@
   }
 
   if (!preprocessor_output_path.empty() && (force || !failed)) {
-    failed = !preprocessHeaders(preprocessor_output_path, header_dir, declaration_database.get());
+    failed = !preprocessHeaders(preprocessor_output_path, location.header_dir, declaration_database.get());
   }
   return failed;
 }