diff --git a/libc/include/string.h b/libc/include/string.h
index c15fe4a..81eaccf 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -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__)