diff --git a/libc/include/string.h b/libc/include/string.h
index e1718e9..b8f60e4 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -122,6 +122,68 @@
     return __builtin___memset_chk(s, c, n, __builtin_object_size (s, 0));
 }
 
+extern size_t strlcpy_real(char *, const char *, size_t)
+    __asm__(__USER_LABEL_PREFIX__ "strlcpy");
+extern void __strlcpy_error()
+    __attribute__((error ("strlcpy called with size bigger than buffer")));
+extern size_t __strlcpy_chk(char *, const char *, size_t, size_t);
+
+__BIONIC_FORTIFY_INLINE
+size_t strlcpy(char *dest, const char *src, size_t size) {
+    size_t bos = __builtin_object_size(dest, 0);
+
+    // Compiler doesn't know destination size. Don't call __strlcpy_chk
+    if (bos == (size_t) -1) {
+        return strlcpy_real(dest, 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(dest, src, size);
+    }
+
+    // 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 > bos)) {
+        __strlcpy_error();
+    }
+
+    return __strlcpy_chk(dest, src, size, bos);
+}
+
+extern size_t strlcat_real(char *, const char *, size_t)
+    __asm__(__USER_LABEL_PREFIX__ "strlcat");
+extern void __strlcat_error()
+    __attribute__((error ("strlcat called with size bigger than buffer")));
+extern size_t __strlcat_chk(char *, const char *, size_t, size_t);
+
+
+__BIONIC_FORTIFY_INLINE
+size_t strlcat(char *dest, const char *src, size_t size) {
+    size_t bos = __builtin_object_size(dest, 0);
+
+    // Compiler doesn't know destination size. Don't call __strlcat_chk
+    if (bos == (size_t) -1) {
+        return strlcat_real(dest, 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(dest, src, size);
+    }
+
+    // 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 > bos)) {
+        __strlcat_error();
+    }
+
+    return __strlcat_chk(dest, src, size, bos);
+}
+
+
 #endif /* defined(__BIONIC_FORTIFY_INLINE) */
 
 __END_DECLS