diff --git a/libc/async_safe/include/async_safe/log.h b/libc/async_safe/include/async_safe/log.h
index 6fdb84f..2f54742 100644
--- a/libc/async_safe/include/async_safe/log.h
+++ b/libc/async_safe/include/async_safe/log.h
@@ -78,14 +78,8 @@
 
 // These functions do return, so callers that want to abort, must do so themselves,
 // or use the macro above.
-void async_safe_fatal_no_abort(const char* _Nonnull fmt, ...) __printflike(1, 2);
-#if defined(__arm__) || defined(__aarch64__) || defined(__x86_64__)
-void async_safe_fatal_va_list(
-    const char* _Nullable prefix, const char* _Nonnull fmt, va_list);
-#else // defined(__mips__) || defined(__i386__)
-void async_safe_fatal_va_list(
-    const char* _Nullable prefix, const char* _Nonnull fmt, va_list _Nonnull);
-#endif
+void async_safe_fatal_no_abort(const char* fmt, ...) __printflike(1, 2);
+void async_safe_fatal_va_list(const char* prefix, const char* fmt, va_list args);
 
 //
 // Formatting routines for the C library's internal debugging.
@@ -93,26 +87,13 @@
 // These are async signal safe, so they can be called from signal handlers.
 //
 
-int async_safe_format_buffer(char* _Nonnull buf, size_t size, const char* _Nonnull fmt, ...) __printflike(3, 4);
+int async_safe_format_buffer(char* buf, size_t size, const char* fmt, ...) __printflike(3, 4);
+int async_safe_format_buffer_va_list(char* buffer, size_t buffer_size, const char* format, va_list args);
 
-#if defined(__arm__) || defined(__aarch64__) || defined(__x86_64__)
-int async_safe_format_buffer_va_list(
-    char* _Nonnull buffer, size_t buffer_size, const char* _Nonnull format, va_list args);
-#else // defined(__mips__) || defined(__i386__)
-int async_safe_format_buffer_va_list(
-    char* _Nonnull buffer, size_t buffer_size, const char* _Nonnull format, va_list _Nonnull args);
-#endif
-
-int async_safe_format_fd(int fd, const char* _Nonnull format , ...) __printflike(2, 3);
-int async_safe_format_log(int pri, const char* _Nonnull tag, const char* _Nonnull fmt, ...) __printflike(3, 4);
-#if defined(__arm__) || defined(__aarch64__) || defined(__x86_64__)
-int async_safe_format_log_va_list(
-    int pri, const char* _Nonnull tag, const char* _Nonnull fmt, va_list ap);
-#else // defined(__mips__) || defined(__i386__)
-int async_safe_format_log_va_list(
-    int pri, const char* _Nonnull tag, const char* _Nonnull fmt, va_list _Nonnull ap);
-#endif
-int async_safe_write_log(int pri, const char* _Nonnull tag, const char* _Nonnull msg);
+int async_safe_format_fd(int fd, const char* format , ...) __printflike(2, 3);
+int async_safe_format_log(int pri, const char* tag, const char* fmt, ...) __printflike(3, 4);
+int async_safe_format_log_va_list( int pri, const char* tag, const char* fmt, va_list ap);
+int async_safe_write_log(int pri, const char* tag, const char* msg);
 
 #define CHECK(predicate) \
   do { \
diff --git a/libc/include/bits/fortify/stdio.h b/libc/include/bits/fortify/stdio.h
index a36ac32..4acefd7 100644
--- a/libc/include/bits/fortify/stdio.h
+++ b/libc/include/bits/fortify/stdio.h
@@ -39,13 +39,12 @@
 #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 {
+              const char * 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 {
+int vsprintf(char *const __pass_object_size dest, const char* format, va_list ap) __overloadable {
     return __builtin___vsprintf_chk(dest, 0, __bos(dest), format, ap);
 }
 #endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
@@ -184,15 +183,13 @@
 
 #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());
+int snprintf(char* dest, size_t size, const char* 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());
+int sprintf(char* dest, const char* format, ...) {
+    return __builtin___sprintf_chk(dest, 0, __bos(dest), format, __builtin_va_arg_pack());
 }
 #endif /* __ANDROID_API__ >= __ANDROID_API_J_MR1__ */
 
diff --git a/libc/include/bits/fortify/string.h b/libc/include/bits/fortify/string.h
index 2fe48d4..0c1999b 100644
--- a/libc/include/bits/fortify/string.h
+++ b/libc/include/bits/fortify/string.h
@@ -30,14 +30,12 @@
 #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);
+void* __memchr_chk(const void*, int, size_t, size_t) __INTRODUCED_IN(23);
+void* __memrchr_chk(const void*, int, size_t, size_t) __INTRODUCED_IN(23);
+char* __stpncpy_chk2(char*, const char*, size_t, size_t, size_t) __INTRODUCED_IN(21);
+char* __strncpy_chk2(char*, const char*, size_t, size_t, size_t) __INTRODUCED_IN(21);
+size_t __strlcpy_chk(char*, const char*, size_t, size_t) __INTRODUCED_IN(17);
+size_t __strlcat_chk(char*, const char*, 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.
@@ -49,47 +47,42 @@
 // 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)
+void* memcpy(void* const dst __pass_object_size0, const void*  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 {
+void* memmove(void* const dst __pass_object_size0, const void* 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 {
+char* stpcpy(char* const dst __pass_object_size, const char* 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 {
+char* strcpy(char* const dst __pass_object_size, const char* 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 {
+char* strcat(char* const dst __pass_object_size, const char* 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 {
+char* strncat(char* const dst __pass_object_size, const char* 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 {
+void* memset(void* const 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__ */
@@ -102,10 +95,6 @@
                 __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");
@@ -128,7 +117,7 @@
 
 #if __ANDROID_API__ >= __ANDROID_API_M__
 __BIONIC_FORTIFY_INLINE
-void* memchr(const void* const _Nonnull s __pass_object_size, int c, size_t n)
+void* memchr(const void* const s __pass_object_size, int c, size_t n)
         __overloadable {
     size_t bos = __bos(s);
 
@@ -140,7 +129,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-void* memrchr(const void* const _Nonnull s __pass_object_size, int c, size_t n)
+void* memrchr(const void* const s __pass_object_size, int c, size_t n)
         __overloadable {
     size_t bos = __bos(s);
 
@@ -154,7 +143,7 @@
 
 #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)
+char* stpncpy(char* const dst __pass_object_size, const char* const src __pass_object_size, size_t n)
         __overloadable {
     size_t bos_dst = __bos(dst);
     size_t bos_src = __bos(src);
@@ -168,7 +157,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-char* strncpy(char* const _Nonnull dst __pass_object_size, const char* const _Nonnull src __pass_object_size, size_t n)
+char* strncpy(char* const dst __pass_object_size, const char* const src __pass_object_size, size_t n)
         __overloadable {
     size_t bos_dst = __bos(dst);
     size_t bos_src = __bos(src);
@@ -184,7 +173,7 @@
 
 #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)
+size_t strlcpy(char* const dst __pass_object_size, const char* src, size_t size)
         __overloadable {
     size_t bos = __bos(dst);
 
@@ -196,7 +185,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-size_t strlcat(char* const _Nonnull dst __pass_object_size, const char* _Nonnull src, size_t size)
+size_t strlcat(char* const dst __pass_object_size, const char* src, size_t size)
         __overloadable {
     size_t bos = __bos(dst);
 
@@ -214,14 +203,14 @@
  * because it's large.
  */
 __BIONIC_FORTIFY_INLINE
-size_t strlen(const char* const _Nonnull s __pass_object_size)
+size_t strlen(const char* const 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)
+size_t strlen(const char* const s __pass_object_size0)
         __overloadable {
     size_t bos = __bos0(s);
 
@@ -236,8 +225,7 @@
 
 #if  __ANDROID_API__ >= __ANDROID_API_J_MR2__
 __BIONIC_FORTIFY_INLINE
-char* strchr(const char* const _Nonnull s __pass_object_size, int c)
-        __overloadable {
+char* strchr(const char* const s __pass_object_size, int c) __overloadable {
     size_t bos = __bos(s);
 
     if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
@@ -248,8 +236,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-char* strrchr(const char* const _Nonnull s __pass_object_size, int c)
-        __overloadable {
+char* strrchr(const char* const s __pass_object_size, int c) __overloadable {
     size_t bos = __bos(s);
 
     if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
@@ -267,12 +254,12 @@
  * 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)
+void* memset(void* 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)))
+void* memset(void* const 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));
 }
@@ -282,7 +269,7 @@
  * flipping size + count will do nothing.
  */
 __BIONIC_ERROR_FUNCTION_VISIBILITY
-void* memset(void* _Nonnull s, int c, size_t n) __overloadable
+void* memset(void* 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? "
@@ -305,7 +292,7 @@
 
 #if __ANDROID_API__ >= __ANDROID_API_M__
 __BIONIC_FORTIFY_INLINE
-void* memchr(const void *_Nonnull s __pass_object_size, int c, size_t n) {
+void* memchr(const void* s __pass_object_size, int c, size_t n) {
     size_t bos = __bos(s);
 
     if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
@@ -345,7 +332,7 @@
 
 #if __ANDROID_API__ >= __ANDROID_API_L__
 __BIONIC_FORTIFY_INLINE
-char* stpncpy(char* _Nonnull dst, const char* _Nonnull src, size_t n) {
+char* stpncpy(char* dst, const char* src, size_t n) {
     size_t bos_dst = __bos(dst);
     size_t bos_src = __bos(src);
 
@@ -366,7 +353,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-char* strncpy(char* _Nonnull dst, const char* _Nonnull src, size_t n) {
+char* strncpy(char* dst, const char* src, size_t n) {
     size_t bos_dst = __bos(dst);
     size_t bos_src = __bos(src);
 
@@ -389,7 +376,7 @@
 
 #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 strlcpy(char* dst __pass_object_size, const char* src, size_t size) {
     size_t bos = __bos(dst);
 
     // Compiler doesn't know destination size. Don't call __strlcpy_chk
@@ -407,7 +394,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-size_t strlcat(char* _Nonnull dst, const char* _Nonnull src, size_t size) {
+size_t strlcat(char* dst, const char* src, size_t size) {
     size_t bos = __bos(dst);
 
     // Compiler doesn't know destination size. Don't call __strlcat_chk
@@ -425,7 +412,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-size_t strlen(const char* _Nonnull s) __overloadable {
+size_t strlen(const char* s) __overloadable {
     size_t bos = __bos(s);
 
     // Compiler doesn't know destination size. Don't call __strlen_chk
@@ -444,7 +431,7 @@
 
 #if  __ANDROID_API__ >= __ANDROID_API_J_MR2__
 __BIONIC_FORTIFY_INLINE
-char* strchr(const char* _Nonnull s, int c) {
+char* strchr(const char* s, int c) {
     size_t bos = __bos(s);
 
     // Compiler doesn't know destination size. Don't call __strchr_chk
@@ -461,7 +448,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-char* strrchr(const char* _Nonnull s, int c) {
+char* strrchr(const char* s, int c) {
     size_t bos = __bos(s);
 
     // Compiler doesn't know destination size. Don't call __strrchr_chk
diff --git a/libc/include/dlfcn.h b/libc/include/dlfcn.h
index 018482d..76bbdb8 100644
--- a/libc/include/dlfcn.h
+++ b/libc/include/dlfcn.h
@@ -34,11 +34,6 @@
 
 __BEGIN_DECLS
 
-#if defined(__clang__)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wnullability-completeness"
-#endif
-
 typedef struct {
   /* Pathname of shared object that contains address. */
   const char* dli_fname;
@@ -51,11 +46,11 @@
 } Dl_info;
 
 void* dlopen(const char* filename, int flag);
-int dlclose(void* _Nonnull handle);
+int dlclose(void* handle);
 char* dlerror(void);
-void* dlsym(void* handle, const char* _Nonnull symbol);
-void* dlvsym(void* handle, const char* _Nonnull symbol, const char* _Nonnull version) __INTRODUCED_IN(24);
-int dladdr(const void* addr, Dl_info* _Nonnull info);
+void* dlsym(void* handle, const char* symbol);
+void* dlvsym(void* handle, const char* symbol, const char* version) __INTRODUCED_IN(24);
+int dladdr(const void* addr, Dl_info* info);
 
 #define RTLD_LOCAL    0
 #define RTLD_LAZY     0x00001
@@ -80,10 +75,6 @@
 #define RTLD_NEXT     __BIONIC_CAST(reinterpret_cast, void*, 0xfffffffe)
 #endif
 
-#if defined(__clang__)
-#pragma clang diagnostic pop
-#endif
-
 __END_DECLS
 
 #endif /* __DLFCN_H */
diff --git a/libc/include/error.h b/libc/include/error.h
index 05ce35d..b145afc 100644
--- a/libc/include/error.h
+++ b/libc/include/error.h
@@ -33,12 +33,12 @@
 
 __BEGIN_DECLS
 
-extern void (* _Nullable error_print_progname)(void) __INTRODUCED_IN(23);
+extern void (*error_print_progname)(void) __INTRODUCED_IN(23);
 extern unsigned int error_message_count __INTRODUCED_IN(23);
 extern int error_one_per_line __INTRODUCED_IN(23);
 
-void error(int, int, const char* _Nonnull, ...) __printflike(3, 4) __INTRODUCED_IN(23);
-void error_at_line(int, int, const char* _Nullable, unsigned int, const char* _Nonnull, ...)
+void error(int, int, const char*, ...) __printflike(3, 4) __INTRODUCED_IN(23);
+void error_at_line(int, int, const char*, unsigned int, const char*, ...)
     __printflike(5, 6) __INTRODUCED_IN(23);
 
 __END_DECLS
diff --git a/libc/include/pthread.h b/libc/include/pthread.h
index 7dec3cc..7165738 100644
--- a/libc/include/pthread.h
+++ b/libc/include/pthread.h
@@ -38,11 +38,6 @@
 
 __BEGIN_DECLS
 
-#if defined(__clang__)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wnullability-completeness"
-#endif
-
 enum {
     PTHREAD_MUTEX_NORMAL = 0,
     PTHREAD_MUTEX_RECURSIVE = 1,
@@ -90,51 +85,48 @@
 
 int pthread_atfork(void (*)(void), void (*)(void), void (*)(void)) __INTRODUCED_IN(12);
 
-int pthread_attr_destroy(pthread_attr_t* _Nonnull);
-int pthread_attr_getdetachstate(const pthread_attr_t* _Nonnull, int* _Nonnull);
-int pthread_attr_getguardsize(const pthread_attr_t* _Nonnull, size_t* _Nonnull);
-int pthread_attr_getschedparam(const pthread_attr_t* _Nonnull, struct sched_param* _Nonnull);
-int pthread_attr_getschedpolicy(const pthread_attr_t* _Nonnull, int* _Nonnull);
-int pthread_attr_getscope(const pthread_attr_t* _Nonnull, int* _Nonnull);
-int pthread_attr_getstack(const pthread_attr_t* _Nonnull, void** _Nonnull, size_t* _Nonnull);
-int pthread_attr_getstacksize(const pthread_attr_t* _Nonnull, size_t* _Nonnull);
-int pthread_attr_init(pthread_attr_t* _Nonnull);
-int pthread_attr_setdetachstate(pthread_attr_t* _Nonnull, int);
-int pthread_attr_setguardsize(pthread_attr_t* _Nonnull, size_t);
-int pthread_attr_setschedparam(pthread_attr_t* _Nonnull, const struct sched_param* _Nonnull);
-int pthread_attr_setschedpolicy(pthread_attr_t* _Nonnull, int);
-int pthread_attr_setscope(pthread_attr_t* _Nonnull, int);
-int pthread_attr_setstack(pthread_attr_t* _Nonnull, void*, size_t);
-int pthread_attr_setstacksize(pthread_attr_t* _Nonnull, size_t);
+int pthread_attr_destroy(pthread_attr_t*);
+int pthread_attr_getdetachstate(const pthread_attr_t*, int*);
+int pthread_attr_getguardsize(const pthread_attr_t*, size_t*);
+int pthread_attr_getschedparam(const pthread_attr_t*, struct sched_param*);
+int pthread_attr_getschedpolicy(const pthread_attr_t*, int*);
+int pthread_attr_getscope(const pthread_attr_t*, int*);
+int pthread_attr_getstack(const pthread_attr_t*, void**, size_t*);
+int pthread_attr_getstacksize(const pthread_attr_t*, size_t*);
+int pthread_attr_init(pthread_attr_t*);
+int pthread_attr_setdetachstate(pthread_attr_t*, int);
+int pthread_attr_setguardsize(pthread_attr_t*, size_t);
+int pthread_attr_setschedparam(pthread_attr_t*, const struct sched_param*);
+int pthread_attr_setschedpolicy(pthread_attr_t*, int);
+int pthread_attr_setscope(pthread_attr_t*, int);
+int pthread_attr_setstack(pthread_attr_t*, void*, size_t);
+int pthread_attr_setstacksize(pthread_attr_t*, size_t);
 
-int pthread_condattr_destroy(pthread_condattr_t* _Nonnull);
-int pthread_condattr_getclock(const pthread_condattr_t* _Nonnull, clockid_t* _Nonnull)
-  __INTRODUCED_IN(21);
-int pthread_condattr_getpshared(const pthread_condattr_t* _Nonnull, int* _Nonnull);
-int pthread_condattr_init(pthread_condattr_t* _Nonnull);
-int pthread_condattr_setclock(pthread_condattr_t* _Nonnull, clockid_t) __INTRODUCED_IN(21);
-int pthread_condattr_setpshared(pthread_condattr_t* _Nonnull, int);
+int pthread_condattr_destroy(pthread_condattr_t*);
+int pthread_condattr_getclock(const pthread_condattr_t*, clockid_t*) __INTRODUCED_IN(21);
+int pthread_condattr_getpshared(const pthread_condattr_t*, int*);
+int pthread_condattr_init(pthread_condattr_t*);
+int pthread_condattr_setclock(pthread_condattr_t*, clockid_t) __INTRODUCED_IN(21);
+int pthread_condattr_setpshared(pthread_condattr_t*, int);
 
-int pthread_cond_broadcast(pthread_cond_t* _Nonnull);
-int pthread_cond_destroy(pthread_cond_t* _Nonnull);
-int pthread_cond_init(pthread_cond_t* _Nonnull, const pthread_condattr_t*);
-int pthread_cond_signal(pthread_cond_t* _Nonnull);
-int pthread_cond_timedwait(pthread_cond_t* _Nonnull, pthread_mutex_t* _Nonnull,
-                           const struct timespec* _Nonnull);
-int pthread_cond_wait(pthread_cond_t* _Nonnull, pthread_mutex_t* _Nonnull);
+int pthread_cond_broadcast(pthread_cond_t*);
+int pthread_cond_destroy(pthread_cond_t*);
+int pthread_cond_init(pthread_cond_t*, const pthread_condattr_t*);
+int pthread_cond_signal(pthread_cond_t*);
+int pthread_cond_timedwait(pthread_cond_t*, pthread_mutex_t*, const struct timespec*);
+int pthread_cond_wait(pthread_cond_t*, pthread_mutex_t*);
 
-int pthread_create(pthread_t* _Nonnull, pthread_attr_t const*,
-                   void* (* _Nonnull start_routine)(void*), void*);
+int pthread_create(pthread_t*, pthread_attr_t const*, void* (*start_routine)(void*), void*);
 int pthread_detach(pthread_t);
 void pthread_exit(void*) __noreturn;
 
 int pthread_equal(pthread_t, pthread_t);
 
-int pthread_getattr_np(pthread_t, pthread_attr_t* _Nonnull);
+int pthread_getattr_np(pthread_t, pthread_attr_t*);
 
-int pthread_getcpuclockid(pthread_t, clockid_t* _Nonnull);
+int pthread_getcpuclockid(pthread_t, clockid_t*);
 
-int pthread_getschedparam(pthread_t, int* _Nonnull, struct sched_param* _Nonnull);
+int pthread_getschedparam(pthread_t, int*, struct sched_param*);
 
 void* pthread_getspecific(pthread_key_t);
 
@@ -142,23 +134,23 @@
 
 int pthread_join(pthread_t, void**);
 
-int pthread_key_create(pthread_key_t* _Nonnull, void (*)(void*));
+int pthread_key_create(pthread_key_t*, void (*)(void*));
 int pthread_key_delete(pthread_key_t);
 
-int pthread_mutexattr_destroy(pthread_mutexattr_t* _Nonnull);
-int pthread_mutexattr_getpshared(const pthread_mutexattr_t* _Nonnull, int* _Nonnull);
-int pthread_mutexattr_gettype(const pthread_mutexattr_t* _Nonnull, int* _Nonnull);
-int pthread_mutexattr_init(pthread_mutexattr_t* _Nonnull);
-int pthread_mutexattr_setpshared(pthread_mutexattr_t* _Nonnull, int);
-int pthread_mutexattr_settype(pthread_mutexattr_t* _Nonnull, int);
+int pthread_mutexattr_destroy(pthread_mutexattr_t*);
+int pthread_mutexattr_getpshared(const pthread_mutexattr_t*, int*);
+int pthread_mutexattr_gettype(const pthread_mutexattr_t*, int*);
+int pthread_mutexattr_init(pthread_mutexattr_t*);
+int pthread_mutexattr_setpshared(pthread_mutexattr_t*, int);
+int pthread_mutexattr_settype(pthread_mutexattr_t*, int);
 
-int pthread_mutex_destroy(pthread_mutex_t* _Nonnull);
-int pthread_mutex_init(pthread_mutex_t* _Nonnull, const pthread_mutexattr_t*);
-int pthread_mutex_lock(pthread_mutex_t* _Nonnull);
-int pthread_mutex_timedlock(pthread_mutex_t* _Nonnull, const struct timespec* _Nonnull)
+int pthread_mutex_destroy(pthread_mutex_t*);
+int pthread_mutex_init(pthread_mutex_t*, const pthread_mutexattr_t*);
+int pthread_mutex_lock(pthread_mutex_t*);
+int pthread_mutex_timedlock(pthread_mutex_t*, const struct timespec* )
   __INTRODUCED_IN(21);
-int pthread_mutex_trylock(pthread_mutex_t* _Nonnull);
-int pthread_mutex_unlock(pthread_mutex_t* _Nonnull);
+int pthread_mutex_trylock(pthread_mutex_t*);
+int pthread_mutex_unlock(pthread_mutex_t*);
 
 #if defined(__LP32__) && __ANDROID_API__ < 21
 /*
@@ -180,59 +172,59 @@
                                        const struct timespec* reltime);
 #endif
 
-int pthread_once(pthread_once_t* _Nonnull, void (* _Nonnull init_routine)(void));
+int pthread_once(pthread_once_t*, void (*init_routine)(void));
 
-int pthread_rwlockattr_init(pthread_rwlockattr_t* _Nonnull);
-int pthread_rwlockattr_destroy(pthread_rwlockattr_t* _Nonnull);
-int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t* _Nonnull, int* _Nonnull);
-int pthread_rwlockattr_setpshared(pthread_rwlockattr_t* _Nonnull, int);
-int pthread_rwlockattr_getkind_np(const pthread_rwlockattr_t* _Nonnull, int* _Nonnull)
+int pthread_rwlockattr_init(pthread_rwlockattr_t*);
+int pthread_rwlockattr_destroy(pthread_rwlockattr_t*);
+int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t*, int*);
+int pthread_rwlockattr_setpshared(pthread_rwlockattr_t*, int);
+int pthread_rwlockattr_getkind_np(const pthread_rwlockattr_t*, int*)
   __INTRODUCED_IN(23);
-int pthread_rwlockattr_setkind_np(pthread_rwlockattr_t* _Nonnull, int) __INTRODUCED_IN(23);
+int pthread_rwlockattr_setkind_np(pthread_rwlockattr_t*, int) __INTRODUCED_IN(23);
 
-int pthread_rwlock_destroy(pthread_rwlock_t* _Nonnull);
-int pthread_rwlock_init(pthread_rwlock_t* _Nonnull, const pthread_rwlockattr_t*);
-int pthread_rwlock_rdlock(pthread_rwlock_t* _Nonnull);
-int pthread_rwlock_timedrdlock(pthread_rwlock_t* _Nonnull, const struct timespec* _Nonnull);
-int pthread_rwlock_timedwrlock(pthread_rwlock_t* _Nonnull, const struct timespec* _Nonnull);
-int pthread_rwlock_tryrdlock(pthread_rwlock_t* _Nonnull);
-int pthread_rwlock_trywrlock(pthread_rwlock_t* _Nonnull);
-int pthread_rwlock_unlock(pthread_rwlock_t* _Nonnull);
-int pthread_rwlock_wrlock(pthread_rwlock_t* _Nonnull);
+int pthread_rwlock_destroy(pthread_rwlock_t*);
+int pthread_rwlock_init(pthread_rwlock_t*, const pthread_rwlockattr_t*);
+int pthread_rwlock_rdlock(pthread_rwlock_t*);
+int pthread_rwlock_timedrdlock(pthread_rwlock_t*, const struct timespec*);
+int pthread_rwlock_timedwrlock(pthread_rwlock_t*, const struct timespec*);
+int pthread_rwlock_tryrdlock(pthread_rwlock_t*);
+int pthread_rwlock_trywrlock(pthread_rwlock_t*);
+int pthread_rwlock_unlock(pthread_rwlock_t*);
+int pthread_rwlock_wrlock(pthread_rwlock_t*);
 
 #if __ANDROID_API__ >= __ANDROID_API_N__
-int pthread_barrierattr_init(pthread_barrierattr_t* _Nonnull attr) __INTRODUCED_IN(24);
-int pthread_barrierattr_destroy(pthread_barrierattr_t* _Nonnull attr) __INTRODUCED_IN(24);
-int pthread_barrierattr_getpshared(const pthread_barrierattr_t* _Nonnull attr,
-                                   int* _Nonnull pshared) __INTRODUCED_IN(24);
-int pthread_barrierattr_setpshared(pthread_barrierattr_t* _Nonnull attr, int pshared)
+int pthread_barrierattr_init(pthread_barrierattr_t* attr) __INTRODUCED_IN(24);
+int pthread_barrierattr_destroy(pthread_barrierattr_t* attr) __INTRODUCED_IN(24);
+int pthread_barrierattr_getpshared(const pthread_barrierattr_t* attr,
+                                   int* pshared) __INTRODUCED_IN(24);
+int pthread_barrierattr_setpshared(pthread_barrierattr_t* attr, int pshared)
   __INTRODUCED_IN(24);
 #endif
 
 #if __ANDROID_API__ >= __ANDROID_API_N__
-int pthread_barrier_init(pthread_barrier_t* _Nonnull, const pthread_barrierattr_t*, unsigned)
+int pthread_barrier_init(pthread_barrier_t*, const pthread_barrierattr_t*, unsigned)
   __INTRODUCED_IN(24);
-int pthread_barrier_destroy(pthread_barrier_t* _Nonnull) __INTRODUCED_IN(24);
-int pthread_barrier_wait(pthread_barrier_t* _Nonnull) __INTRODUCED_IN(24);
+int pthread_barrier_destroy(pthread_barrier_t*) __INTRODUCED_IN(24);
+int pthread_barrier_wait(pthread_barrier_t*) __INTRODUCED_IN(24);
 #endif
 
 #if __ANDROID_API__ >= __ANDROID_API_N__
-int pthread_spin_destroy(pthread_spinlock_t* _Nonnull) __INTRODUCED_IN(24);
-int pthread_spin_init(pthread_spinlock_t* _Nonnull, int) __INTRODUCED_IN(24);
-int pthread_spin_lock(pthread_spinlock_t* _Nonnull) __INTRODUCED_IN(24);
-int pthread_spin_trylock(pthread_spinlock_t* _Nonnull) __INTRODUCED_IN(24);
-int pthread_spin_unlock(pthread_spinlock_t* _Nonnull) __INTRODUCED_IN(24);
+int pthread_spin_destroy(pthread_spinlock_t*) __INTRODUCED_IN(24);
+int pthread_spin_init(pthread_spinlock_t*, int) __INTRODUCED_IN(24);
+int pthread_spin_lock(pthread_spinlock_t*) __INTRODUCED_IN(24);
+int pthread_spin_trylock(pthread_spinlock_t*) __INTRODUCED_IN(24);
+int pthread_spin_unlock(pthread_spinlock_t*) __INTRODUCED_IN(24);
 #endif
 
 pthread_t pthread_self(void) __attribute_const__;
 
 #if defined(__USE_GNU)
-int pthread_getname_np(pthread_t, char* _Nonnull, size_t) __INTRODUCED_IN(26);
+int pthread_getname_np(pthread_t, char*, size_t) __INTRODUCED_IN(26);
 #endif
 /* TODO: this should be __USE_GNU too. */
-int pthread_setname_np(pthread_t, const char* _Nonnull);
+int pthread_setname_np(pthread_t, const char*);
 
-int pthread_setschedparam(pthread_t, int, const struct sched_param* _Nonnull);
+int pthread_setschedparam(pthread_t, int, const struct sched_param*);
 
 int pthread_setspecific(pthread_key_t, const void*);
 
@@ -262,10 +254,6 @@
         __pthread_cleanup_pop( &__cleanup, (execute)); \
     } while (0);                                       \
 
-#if defined(__clang__)
-#pragma clang diagnostic pop
-#endif
-
 __END_DECLS
 
 #endif /* _PTHREAD_H_ */
diff --git a/libc/include/signal.h b/libc/include/signal.h
index 1400328..89d85fc 100644
--- a/libc/include/signal.h
+++ b/libc/include/signal.h
@@ -54,11 +54,6 @@
 
 __BEGIN_DECLS
 
-#if defined(__clang__)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wnullability-completeness"
-#endif
-
 typedef int sig_atomic_t;
 
 /* The arm and x86 kernel header files don't define _NSIG. */
@@ -129,10 +124,10 @@
 // Implemented as static inlines before 21.
 #endif
 
-int sigpending(sigset_t* _Nonnull);
+int sigpending(sigset_t*);
 int sigprocmask(int, const sigset_t*, sigset_t*);
-int sigsuspend(const sigset_t* _Nonnull);
-int sigwait(const sigset_t* _Nonnull, int* _Nonnull);
+int sigsuspend(const sigset_t*);
+int sigwait(const sigset_t*, int*);
 
 int sighold(int)
   __attribute__((deprecated("use sigprocmask() or pthread_sigmask() instead")))
@@ -161,12 +156,8 @@
 int pthread_sigmask(int, const sigset_t*, sigset_t*);
 
 int sigqueue(pid_t, int, const union sigval) __INTRODUCED_IN(23);
-int sigtimedwait(const sigset_t* _Nonnull, siginfo_t*, const struct timespec*) __INTRODUCED_IN(23);
-int sigwaitinfo(const sigset_t* _Nonnull, siginfo_t*) __INTRODUCED_IN(23);
-
-#if defined(__clang__)
-#pragma clang diagnostic pop
-#endif
+int sigtimedwait(const sigset_t*, siginfo_t*, const struct timespec*) __INTRODUCED_IN(23);
+int sigwaitinfo(const sigset_t*, siginfo_t*) __INTRODUCED_IN(23);
 
 __END_DECLS
 
diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index a9bb124..7e5a976 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -52,11 +52,6 @@
 
 __BEGIN_DECLS
 
-#if defined(__clang__)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wnullability-completeness"
-#endif
-
 typedef off_t fpos_t;
 typedef off64_t fpos64_t;
 
@@ -119,12 +114,12 @@
 int	 fgetc(FILE *);
 char	*fgets(char *, int, FILE *) __overloadable
   __RENAME_CLANG(fgets);
-int	 fprintf(FILE * , const char * _Nonnull, ...) __printflike(2, 3);
+int	 fprintf(FILE * , const char *, ...) __printflike(2, 3);
 int	 fputc(int, FILE *);
 int	 fputs(const char *, FILE *);
 size_t	 fread(void *, size_t, size_t, FILE *)
       __overloadable __RENAME_CLANG(fread);
-int	 fscanf(FILE *, const char * _Nonnull, ...) __scanflike(2, 3);
+int	 fscanf(FILE *, const char *, ...) __scanflike(2, 3);
 size_t	 fwrite(const void *, size_t, size_t, FILE *)
     __overloadable __RENAME_CLANG(fwrite);
 int	 getc(FILE *);
@@ -133,23 +128,23 @@
 ssize_t getline(char**, size_t*, FILE*) __INTRODUCED_IN(18);
 
 void	 perror(const char *);
-int	 printf(const char * _Nonnull, ...) __printflike(1, 2);
+int	 printf(const char *, ...) __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 * _Nonnull, ...) __scanflike(1, 2);
+int	 scanf(const char *, ...) __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	 sscanf(const char *, const char *, ...) __scanflike(2, 3);
 int	 ungetc(int, FILE *);
-int	 vfprintf(FILE *, const char * _Nonnull, va_list) __printflike(2, 0);
-int	 vprintf(const char * _Nonnull, va_list) __printflike(1, 0);
+int	 vfprintf(FILE *, const char *, va_list) __printflike(2, 0);
+int	 vprintf(const char *, va_list) __printflike(1, 0);
 
 #if __ANDROID_API__ >= 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);
+int dprintf(int, const char*, ...) __printflike(2, 3) __INTRODUCED_IN(21);
+int vdprintf(int, const char*, 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
@@ -158,18 +153,18 @@
  * 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* _Nonnull, ...) __printflike(2, 3) __RENAME(fdprintf);
-int vdprintf(int, const char* _Nonnull, va_list) __printflike(2, 0) __RENAME(vfdprintf);
+int dprintf(int, const char*, ...) __printflike(2, 3) __RENAME(fdprintf);
+int vdprintf(int, const char*, 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*, const char* _Nonnull, ...)
+int sprintf(char*, const char*, ...)
     __printflike(2, 3) __warnattr_strict("sprintf is often misused; please use snprintf")
     __overloadable __RENAME_CLANG(sprintf);
-int vsprintf(char*, const char* _Nonnull, va_list)
+int vsprintf(char*, const char*, va_list)
     __overloadable __printflike(2, 0) __RENAME_CLANG(vsprintf)
     __warnattr_strict("vsprintf is often misused; please use vsnprintf");
 char* tmpnam(char*)
@@ -226,13 +221,13 @@
 FILE* tmpfile(void);
 FILE* tmpfile64(void) __INTRODUCED_IN(24);
 
-int snprintf(char*, size_t, const char* _Nonnull, ...)
+int snprintf(char*, size_t, const char*, ...)
     __printflike(3, 4) __overloadable __RENAME_CLANG(snprintf);
-int vfscanf(FILE*, const char* _Nonnull, va_list) __scanflike(2, 0);
-int vscanf(const char* _Nonnull , va_list) __scanflike(1, 0);
-int vsnprintf(char*, size_t, const char* _Nonnull, va_list)
+int vfscanf(FILE*, const char*, va_list) __scanflike(2, 0);
+int vscanf(const char* , va_list) __scanflike(1, 0);
+int vsnprintf(char*, size_t, const char*, va_list)
     __printflike(3, 0) __overloadable __RENAME_CLANG(vsnprintf);
-int vsscanf(const char* _Nonnull, const char* _Nonnull, va_list) __scanflike(2, 0);
+int vsscanf(const char*, const char*, va_list) __scanflike(2, 0);
 
 #define L_ctermid 1024 /* size for ctermid() */
 char* ctermid(char*) __INTRODUCED_IN(26);
@@ -253,12 +248,12 @@
 FILE* open_memstream(char**, size_t*) __INTRODUCED_IN(23);
 
 #if defined(__USE_BSD) || defined(__BIONIC__) /* Historically bionic exposed these. */
-int  asprintf(char**, const char* _Nonnull, ...) __printflike(2, 3);
+int  asprintf(char**, const char*, ...) __printflike(2, 3);
 char* fgetln(FILE*, size_t*);
 int fpurge(FILE*);
 void setbuffer(FILE*, char*, int);
 int setlinebuf(FILE*);
-int vasprintf(char**, const char* _Nonnull, va_list) __printflike(2, 0);
+int vasprintf(char**, const char*, 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);
@@ -271,10 +266,6 @@
 #include <bits/fortify/stdio.h>
 #endif
 
-#if defined(__clang__)
-#pragma clang diagnostic pop
-#endif
-
 __END_DECLS
 
 #endif /* _STDIO_H_ */
diff --git a/libc/include/string.h b/libc/include/string.h
index 8b4fa27..631b3dd 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -37,64 +37,52 @@
 
 __BEGIN_DECLS
 
-#if defined(__clang__)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wnullability-completeness"
-#endif
-
 #if defined(__USE_BSD)
 #include <strings.h>
 #endif
 
-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, const void* _Nonnull, size_t)
+void* memccpy(void*, const void*, int, size_t);
+void* memchr(const void*, int, size_t) __attribute_pure__ __overloadable __RENAME_CLANG(memchr);
+void* memrchr(const void*, int, size_t) __attribute_pure__ __overloadable __RENAME_CLANG(memrchr);
+int memcmp(const void*, const void*, size_t) __attribute_pure__;
+void* memcpy(void*, const void*, size_t)
         __overloadable __RENAME_CLANG(memcpy);
 #if defined(__USE_GNU)
-void* mempcpy(void* _Nonnull, const void* _Nonnull, size_t) __INTRODUCED_IN(23);
+void* mempcpy(void*, const void*, size_t) __INTRODUCED_IN(23);
 #endif
-void* memmove(void* _Nonnull, const void* _Nonnull, size_t) __overloadable
-        __RENAME_CLANG(memmove);
-void* memset(void* _Nonnull, int, size_t) __overloadable __RENAME_CLANG(memset);
-void* memmem(const void* _Nonnull, size_t, const void* _Nonnull, size_t) __attribute_pure__;
+void* memmove(void*, const void*, size_t) __overloadable __RENAME_CLANG(memmove);
+void* memset(void*, int, size_t) __overloadable __RENAME_CLANG(memset);
+void* memmem(const void*, size_t, const void*, size_t) __attribute_pure__;
 
-char* strchr(const char* _Nonnull, int) __attribute_pure__ __overloadable
-        __RENAME_CLANG(strchr);
-char* __strchr_chk(const char* _Nonnull, int, size_t) __INTRODUCED_IN(18);
+char* strchr(const char*, int) __attribute_pure__ __overloadable __RENAME_CLANG(strchr);
+char* __strchr_chk(const char*, int, size_t) __INTRODUCED_IN(18);
 #if defined(__USE_GNU)
 #if defined(__cplusplus)
-extern "C++" char* strchrnul(char* _Nonnull, int) __RENAME(strchrnul) __attribute_pure__ __INTRODUCED_IN(24);
-extern "C++" const char* strchrnul(const char* _Nonnull, int) __RENAME(strchrnul) __attribute_pure__ __INTRODUCED_IN(24);
+extern "C++" char* strchrnul(char*, int) __RENAME(strchrnul) __attribute_pure__ __INTRODUCED_IN(24);
+extern "C++" const char* strchrnul(const char*, int) __RENAME(strchrnul) __attribute_pure__ __INTRODUCED_IN(24);
 #else
-char* strchrnul(const char* _Nonnull, int) __attribute_pure__ __INTRODUCED_IN(24);
+char* strchrnul(const char*, int) __attribute_pure__ __INTRODUCED_IN(24);
 #endif
 #endif
 
-char* strrchr(const char* _Nonnull, int) __attribute_pure__ __overloadable
-        __RENAME_CLANG(strrchr);
-char* __strrchr_chk(const char* _Nonnull, int, size_t) __INTRODUCED_IN(18);
+char* strrchr(const char*, int) __attribute_pure__ __overloadable __RENAME_CLANG(strrchr);
+char* __strrchr_chk(const char*, int, size_t) __INTRODUCED_IN(18);
 
-size_t strlen(const char* _Nonnull) __attribute_pure__ __overloadable
+size_t strlen(const char*) __attribute_pure__ __overloadable
         __RENAME_CLANG(strlen);
-size_t __strlen_chk(const char* _Nonnull, size_t) __INTRODUCED_IN(17);
+size_t __strlen_chk(const char*, size_t) __INTRODUCED_IN(17);
 
-int strcmp(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
-char* stpcpy(char* _Nonnull, const char* _Nonnull)
-        __overloadable __RENAME_CLANG(stpcpy) __INTRODUCED_IN(21);
-char* strcpy(char* _Nonnull, const char* _Nonnull)
+int strcmp(const char*, const char*) __attribute_pure__;
+char* stpcpy(char*, const char*) __overloadable __RENAME_CLANG(stpcpy) __INTRODUCED_IN(21);
+char* strcpy(char*, const char*)
         __overloadable __RENAME_CLANG(strcpy);
-char* strcat(char* _Nonnull, const char* _Nonnull)
-        __overloadable __RENAME_CLANG(strcat);
-char* strdup(const char* _Nonnull);
+char* strcat(char*, const char*) __overloadable __RENAME_CLANG(strcat);
+char* strdup(const char*);
 
-char* strstr(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
-char* strcasestr(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
-char* strtok(char*, const char* _Nonnull);
-char* strtok_r(char*, const char* _Nonnull, char** _Nonnull);
+char* strstr(const char*, const char*) __attribute_pure__;
+char* strcasestr(const char*, const char*) __attribute_pure__;
+char* strtok(char*, const char*);
+char* strtok_r(char*, const char*, char**);
 
 char* strerror(int);
 char* strerror_l(int, locale_t) __INTRODUCED_IN(23);
@@ -104,34 +92,29 @@
 int strerror_r(int, char*, size_t);
 #endif
 
-size_t strnlen(const char* _Nonnull, size_t) __attribute_pure__;
-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, const char* _Nonnull, size_t)
-        __overloadable __RENAME_CLANG(stpncpy) __INTRODUCED_IN(21);
-char* strncpy(char* _Nonnull, const char* _Nonnull, size_t)
-        __overloadable __RENAME_CLANG(strncpy);
+size_t strnlen(const char*, size_t) __attribute_pure__;
+char* strncat(char*, const char*, size_t) __overloadable __RENAME_CLANG(strncat);
+char* strndup(const char*, size_t);
+int strncmp(const char*, const char*, size_t) __attribute_pure__;
+char* stpncpy(char*, const char*, size_t) __overloadable __RENAME_CLANG(stpncpy) __INTRODUCED_IN(21);
+char* strncpy(char*, const char*, size_t) __overloadable __RENAME_CLANG(strncpy);
 
-size_t strlcat(char* _Nonnull, const char* _Nonnull, size_t)
-        __overloadable __RENAME_CLANG(strlcat);
-size_t strlcpy(char* _Nonnull, const char* _Nonnull, size_t)
-        __overloadable __RENAME_CLANG(strlcpy);
+size_t strlcat(char*, const char*, size_t) __overloadable __RENAME_CLANG(strlcat);
+size_t strlcpy(char*, const char*, 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, const char* _Nonnull);
-size_t strspn(const char* _Nonnull, const char* _Nonnull);
+size_t strcspn(const char*, const char*) __attribute_pure__;
+char* strpbrk(const char*, const char*) __attribute_pure__;
+char* strsep(char**, const char*);
+size_t strspn(const char*, const char*);
 
 char* strsignal(int);
 
-int strcoll(const char* _Nonnull, const char* _Nonnull) __attribute_pure__;
-size_t strxfrm(char*, const char* _Nonnull, size_t);
+int strcoll(const char*, const char*) __attribute_pure__;
+size_t strxfrm(char*, const char*, 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*, const char* _Nonnull, size_t, locale_t) __INTRODUCED_IN(21);
+int strcoll_l(const char*, const char*, locale_t) __attribute_pure__ __INTRODUCED_IN(21);
+size_t strxfrm_l(char*, const char*, size_t, locale_t) __INTRODUCED_IN(21);
 #else
 // Implemented as static inlines before 21.
 #endif
@@ -142,10 +125,10 @@
  * It doesn't modify its argument, and in C++ it's const-correct.
  */
 #if defined(__cplusplus)
-extern "C++" char* basename(char* _Nonnull) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
-extern "C++" const char* basename(const char* _Nonnull) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+extern "C++" char* basename(char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+extern "C++" const char* basename(const char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
 #else
-char* basename(const char* _Nonnull) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+char* basename(const char*) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
 #endif
 #endif
 
@@ -162,87 +145,83 @@
 #define __prefer_this_overload __enable_if(true, "preferred overload") __enable_if(true, "")
 extern "C++" {
 inline __always_inline
-void* __bionic_memchr(const void* const _Nonnull s __pass_object_size, int c, size_t n) {
+void* __bionic_memchr(const void* const s __pass_object_size, int c, size_t n) {
     return memchr(s, c, n);
 }
 
 inline __always_inline
-const void* memchr(const void* const _Nonnull s __pass_object_size, int c, size_t n)
+const void* memchr(const void* const s __pass_object_size, int c, size_t n)
         __prefer_this_overload {
     return __bionic_memchr(s, c, n);
 }
 
 inline __always_inline
-void* memchr(void* const _Nonnull s __pass_object_size, int c, size_t n) __prefer_this_overload {
+void* memchr(void* const s __pass_object_size, int c, size_t n) __prefer_this_overload {
     return __bionic_memchr(s, c, n);
 }
 
 inline __always_inline
-char* __bionic_strchr(const char* const _Nonnull s __pass_object_size, int c) {
+char* __bionic_strchr(const char* const s __pass_object_size, int c) {
     return strchr(s, c);
 }
 
 inline __always_inline
-const char* strchr(const char* const _Nonnull s __pass_object_size, int c)
+const char* strchr(const char* const s __pass_object_size, int c)
         __prefer_this_overload {
     return __bionic_strchr(s, c);
 }
 
 inline __always_inline
-char* strchr(char* const _Nonnull s __pass_object_size, int c)
+char* strchr(char* const s __pass_object_size, int c)
         __prefer_this_overload {
     return __bionic_strchr(s, c);
 }
 
 inline __always_inline
-char* __bionic_strrchr(const char* const _Nonnull s __pass_object_size, int c) {
+char* __bionic_strrchr(const char* const s __pass_object_size, int c) {
     return strrchr(s, c);
 }
 
 inline __always_inline
-const char* strrchr(const char* const _Nonnull s __pass_object_size, int c) __prefer_this_overload {
+const char* strrchr(const char* const s __pass_object_size, int c) __prefer_this_overload {
     return __bionic_strrchr(s, c);
 }
 
 inline __always_inline
-char* strrchr(char* const _Nonnull s __pass_object_size, int c) __prefer_this_overload {
+char* strrchr(char* const s __pass_object_size, int c) __prefer_this_overload {
     return __bionic_strrchr(s, c);
 }
 
 /* Functions with no FORTIFY counterpart. */
 inline __always_inline
-char* __bionic_strstr(const char* _Nonnull h, const char* _Nonnull n) { return strstr(h, n); }
+char* __bionic_strstr(const char* h, const char* n) { return strstr(h, n); }
 
 inline __always_inline
-const char* strstr(const char* _Nonnull h, const char* _Nonnull n) __prefer_this_overload {
+const char* strstr(const char* h, const char* n) __prefer_this_overload {
     return __bionic_strstr(h, n);
 }
 
 inline __always_inline
-char* strstr(char* _Nonnull h, const char* _Nonnull n) __prefer_this_overload {
+char* strstr(char* h, const char* n) __prefer_this_overload {
     return __bionic_strstr(h, n);
 }
 
 inline __always_inline
-char* __bionic_strpbrk(const char* _Nonnull h, const char* _Nonnull n) { return strpbrk(h, n); }
+char* __bionic_strpbrk(const char* h, const char* n) { return strpbrk(h, n); }
 
 inline __always_inline
-char* strpbrk(char* _Nonnull h, const char* _Nonnull n) __prefer_this_overload {
+char* strpbrk(char* h, const char* n) __prefer_this_overload {
     return __bionic_strpbrk(h, n);
 }
 
 inline __always_inline
-const char* strpbrk(const char* _Nonnull h, const char* _Nonnull n) __prefer_this_overload {
+const char* strpbrk(const char* h, const char* n) __prefer_this_overload {
     return __bionic_strpbrk(h, n);
 }
 }
 #undef __prefer_this_overload
 #endif
 
-#if defined(__clang__)
-#pragma clang diagnostic pop
-#endif
-
 __END_DECLS
 
 #endif /* _STRING_H */
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index 9c662ba..9541520 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -111,39 +111,6 @@
 #define __unused __attribute__((__unused__))
 #define __used __attribute__((__used__))
 
-/*
- * _Nonnull is similar to the nonnull attribute in that it will instruct
- * compilers to warn the user if it can prove that a null argument is being
- * passed. Unlike the nonnull attribute, this annotation indicated that a value
- * *should not* be null, not that it *cannot* be null, or even that the behavior
- * is undefined. The important distinction is that the optimizer will perform
- * surprising optimizations like the following:
- *
- *     void foo(void*) __attribute__(nonnull, 1);
- *
- *     int bar(int* p) {
- *       foo(p);
- *
- *       // The following null check will be elided because nonnull attribute
- *       // means that, since we call foo with p, p can be assumed to not be
- *       // null. Thus this will crash if we are called with a null pointer.
- *       if (p != NULL) {
- *         return *p;
- *       }
- *       return 0;
- *     }
- *
- *     int main() {
- *       return bar(NULL);
- *     }
- *
- * http://clang.llvm.org/docs/AttributeReference.html#nonnull
- */
-#if !(defined(__clang__) && __has_feature(nullability))
-#define _Nonnull
-#define _Nullable
-#endif
-
 #define __printflike(x, y) __attribute__((__format__(printf, x, y)))
 #define __scanflike(x, y) __attribute__((__format__(scanf, x, y)))
 
diff --git a/libc/include/sys/signalfd.h b/libc/include/sys/signalfd.h
index 79f9490..1e4d464 100644
--- a/libc/include/sys/signalfd.h
+++ b/libc/include/sys/signalfd.h
@@ -36,7 +36,7 @@
 
 __BEGIN_DECLS
 
-int signalfd(int fd, const sigset_t* _Nonnull mask, int flags) __INTRODUCED_IN(18);
+int signalfd(int fd, const sigset_t* mask, int flags) __INTRODUCED_IN(18);
 
 __END_DECLS
 
diff --git a/libc/include/sys/statvfs.h b/libc/include/sys/statvfs.h
index 5df4160..0f421a4 100644
--- a/libc/include/sys/statvfs.h
+++ b/libc/include/sys/statvfs.h
@@ -59,10 +59,10 @@
 #define ST_NODIRATIME  0x0800
 #define ST_RELATIME    0x1000
 
-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);
+int statvfs(const char*, struct statvfs*) __INTRODUCED_IN(19);
+int statvfs64(const char*, struct statvfs64*) __INTRODUCED_IN(21);
+int fstatvfs(int, struct statvfs*) __INTRODUCED_IN(19);
+int fstatvfs64(int, struct statvfs64*) __INTRODUCED_IN(21);
 
 __END_DECLS
 
diff --git a/libc/include/sys/swap.h b/libc/include/sys/swap.h
index 3444736..e79af97 100644
--- a/libc/include/sys/swap.h
+++ b/libc/include/sys/swap.h
@@ -38,8 +38,8 @@
 #define SWAP_FLAG_PRIO_MASK 0x7fff
 #define SWAP_FLAG_PRIO_SHIFT 0
 
-int swapon(const char* _Nonnull, int) __INTRODUCED_IN(19);
-int swapoff(const char* _Nonnull) __INTRODUCED_IN(19);
+int swapon(const char*, int) __INTRODUCED_IN(19);
+int swapoff(const char*) __INTRODUCED_IN(19);
 
 __END_DECLS
 
diff --git a/libc/include/sys/vfs.h b/libc/include/sys/vfs.h
index 1231eb1..3078683 100644
--- a/libc/include/sys/vfs.h
+++ b/libc/include/sys/vfs.h
@@ -137,10 +137,10 @@
 #define XENIX_SUPER_MAGIC     0x012FF7B4
 #define XFS_SUPER_MAGIC       0x58465342
 
-int statfs(const char* _Nonnull, struct statfs* _Nonnull);
-int statfs64(const char* _Nonnull, struct statfs64* _Nonnull) __INTRODUCED_IN(21);
-int fstatfs(int, struct statfs* _Nonnull);
-int fstatfs64(int, struct statfs64* _Nonnull) __INTRODUCED_IN(21);
+int statfs(const char*, struct statfs*);
+int statfs64(const char*, struct statfs64*) __INTRODUCED_IN(21);
+int fstatfs(int, struct statfs*);
+int fstatfs64(int, struct statfs64*) __INTRODUCED_IN(21);
 
 __END_DECLS
 
diff --git a/libc/include/syslog.h b/libc/include/syslog.h
index 4b7eecb..8000f03 100644
--- a/libc/include/syslog.h
+++ b/libc/include/syslog.h
@@ -86,14 +86,10 @@
 #define LOG_PERROR 0x20
 
 void closelog(void);
-void openlog(const char* _Nullable, int, int);
+void openlog(const char*, int, int);
 int setlogmask(int);
-void syslog(int, const char* _Nonnull, ...) __printflike(2, 3);
-#if defined(__arm__) || defined(__aarch64__) || defined(__x86_64__)
-void vsyslog(int, const char* _Nonnull, va_list) __printflike(2, 0);
-#else /* defined(__mips__) || defined(__i386__) */
-void vsyslog(int, const char* _Nonnull, va_list _Nonnull) __printflike(2, 0);
-#endif
+void syslog(int, const char*, ...) __printflike(2, 3);
+void vsyslog(int, const char*, va_list) __printflike(2, 0);
 
 __END_DECLS
 
diff --git a/libc/include/wchar.h b/libc/include/wchar.h
index a86c8a9..4494cb0 100644
--- a/libc/include/wchar.h
+++ b/libc/include/wchar.h
@@ -42,11 +42,6 @@
 
 __BEGIN_DECLS
 
-#if defined(__clang__)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wnullability-completeness"
-#endif
-
 wint_t            btowc(int);
 int               fwprintf(FILE *, const wchar_t *, ...);
 int               fwscanf(FILE *, const wchar_t *, ...);
@@ -125,9 +120,9 @@
 unsigned long long wcstoull_l(const wchar_t*, wchar_t**, int, locale_t) __INTRODUCED_IN(21);
 long double wcstold_l(const wchar_t*, wchar_t**, locale_t) __INTRODUCED_IN(21);
 
-int wcscoll_l(const wchar_t* _Nonnull, const wchar_t* _Nonnull, locale_t) __attribute_pure__
+int wcscoll_l(const wchar_t*, const wchar_t*, locale_t) __attribute_pure__
     __INTRODUCED_IN(21);
-size_t wcsxfrm_l(wchar_t*, const wchar_t* _Nonnull, size_t, locale_t) __INTRODUCED_IN(21);
+size_t wcsxfrm_l(wchar_t*, const wchar_t*, size_t, locale_t) __INTRODUCED_IN(21);
 #else
 // Implemented as static inlines before 21.
 #endif
@@ -139,10 +134,6 @@
 wchar_t* wcsdup(const wchar_t*);
 size_t wcsnlen(const wchar_t*, size_t);
 
-#if defined(__clang__)
-#pragma clang diagnostic pop
-#endif
-
 __END_DECLS
 
 #endif /* _WCHAR_H_ */