diff --git a/posix/bits/unistd.h b/posix/bits/unistd.h
index bd209ec28e..2757b0619a 100644
--- a/posix/bits/unistd.h
+++ b/posix/bits/unistd.h
@@ -22,8 +22,12 @@
 
 # include <bits/unistd-decl.h>
 
-__fortify_function __wur ssize_t
-read (int __fd, void *__buf, size_t __nbytes)
+__fortify_function __attribute_overloadable__ __wur ssize_t
+read (int __fd, __fortify_clang_overload_arg0 (void *, ,__buf), size_t __nbytes)
+     __fortify_clang_warning_only_if_bos0_lt (__nbytes, __buf,
+					      "read called with bigger length than "
+					      "size of the destination buffer")
+
 {
   return __glibc_fortify (read, __nbytes, sizeof (char),
 			  __glibc_objsize0 (__buf),
@@ -32,16 +36,24 @@ read (int __fd, void *__buf, size_t __nbytes)
 
 #if defined __USE_UNIX98 || defined __USE_XOPEN2K8
 # ifndef __USE_FILE_OFFSET64
-__fortify_function __wur ssize_t
-pread (int __fd, void *__buf, size_t __nbytes, __off_t __offset)
+__fortify_function __attribute_overloadable__ __wur ssize_t
+pread (int __fd, __fortify_clang_overload_arg0 (void *, ,__buf),
+       size_t __nbytes, __off_t __offset)
+     __fortify_clang_warning_only_if_bos0_lt (__nbytes, __buf,
+					      "pread called with bigger length than "
+					      "size of the destination buffer")
 {
   return __glibc_fortify (pread, __nbytes, sizeof (char),
 			  __glibc_objsize0 (__buf),
 			  __fd, __buf, __nbytes, __offset);
 }
 # else
-__fortify_function __wur ssize_t
-pread (int __fd, void *__buf, size_t __nbytes, __off64_t __offset)
+__fortify_function __attribute_overloadable__ __wur ssize_t
+pread (int __fd, __fortify_clang_overload_arg0 (void *, ,__buf),
+       size_t __nbytes, __off64_t __offset)
+     __fortify_clang_warning_only_if_bos0_lt (__nbytes, __buf,
+					      "pread called with bigger length than "
+					      "size of the destination buffer")
 {
   return __glibc_fortify (pread64, __nbytes, sizeof (char),
 			  __glibc_objsize0 (__buf),
@@ -50,8 +62,12 @@ pread (int __fd, void *__buf, size_t __nbytes, __off64_t __offset)
 # endif
 
 # ifdef __USE_LARGEFILE64
-__fortify_function __wur ssize_t
-pread64 (int __fd, void *__buf, size_t __nbytes, __off64_t __offset)
+__fortify_function __attribute_overloadable__ __wur ssize_t
+pread64 (int __fd, __fortify_clang_overload_arg0 (void *, ,__buf),
+	 size_t __nbytes, __off64_t __offset)
+     __fortify_clang_warning_only_if_bos0_lt (__nbytes, __buf,
+					      "pread64 called with bigger length than "
+					      "size of the destination buffer")
 {
   return __glibc_fortify (pread64, __nbytes, sizeof (char),
 			  __glibc_objsize0 (__buf),
@@ -61,9 +77,14 @@ pread64 (int __fd, void *__buf, size_t __nbytes, __off64_t __offset)
 #endif
 
 #if defined __USE_XOPEN_EXTENDED || defined __USE_XOPEN2K
-__fortify_function __nonnull ((1, 2)) __wur ssize_t
-__NTH (readlink (const char *__restrict __path, char *__restrict __buf,
+__fortify_function __attribute_overloadable__ __nonnull ((1, 2)) __wur ssize_t
+__NTH (readlink (const char *__restrict __path,
+		 __fortify_clang_overload_arg0 (char *, __restrict, __buf),
 		 size_t __len))
+     __fortify_clang_warning_only_if_bos_lt (__len, __buf,
+					     "readlink called with bigger length "
+					     "than size of destination buffer")
+
 {
   return __glibc_fortify (readlink, __len, sizeof (char),
 			  __glibc_objsize (__buf),
@@ -72,9 +93,13 @@ __NTH (readlink (const char *__restrict __path, char *__restrict __buf,
 #endif
 
 #ifdef __USE_ATFILE
-__fortify_function __nonnull ((2, 3)) __wur ssize_t
+__fortify_function __attribute_overloadable__ __nonnull ((2, 3)) __wur ssize_t
 __NTH (readlinkat (int __fd, const char *__restrict __path,
-		   char *__restrict __buf, size_t __len))
+		   __fortify_clang_overload_arg0 (char *, __restrict, __buf),
+		   size_t __len))
+     __fortify_clang_warning_only_if_bos_lt (__len, __buf,
+					     "readlinkat called with bigger length "
+					     "than size of destination buffer")
 {
   return __glibc_fortify (readlinkat, __len, sizeof (char),
 			  __glibc_objsize (__buf),
@@ -82,8 +107,11 @@ __NTH (readlinkat (int __fd, const char *__restrict __path,
 }
 #endif
 
-__fortify_function __wur char *
-__NTH (getcwd (char *__buf, size_t __size))
+__fortify_function __attribute_overloadable__ __wur char *
+__NTH (getcwd (__fortify_clang_overload_arg (char *, , __buf), size_t __size))
+     __fortify_clang_warning_only_if_bos_lt (__size, __buf,
+					     "getcwd called with bigger length "
+					     "than size of destination buffer")
 {
   return __glibc_fortify (getcwd, __size, sizeof (char),
 			  __glibc_objsize (__buf),
@@ -91,8 +119,9 @@ __NTH (getcwd (char *__buf, size_t __size))
 }
 
 #if defined __USE_MISC || defined __USE_XOPEN_EXTENDED
-__fortify_function __nonnull ((1)) __attribute_deprecated__ __wur char *
-__NTH (getwd (char *__buf))
+__fortify_function __attribute_overloadable__ __nonnull ((1))
+__attribute_deprecated__ __wur char *
+__NTH (getwd (__fortify_clang_overload_arg (char *,, __buf)))
 {
   if (__glibc_objsize (__buf) != (size_t) -1)
     return __getwd_chk (__buf, __glibc_objsize (__buf));
@@ -100,8 +129,12 @@ __NTH (getwd (char *__buf))
 }
 #endif
 
-__fortify_function size_t
-__NTH (confstr (int __name, char *__buf, size_t __len))
+__fortify_function __attribute_overloadable__ size_t
+__NTH (confstr (int __name, __fortify_clang_overload_arg (char *, ,__buf),
+		size_t __len))
+     __fortify_clang_warning_only_if_bos_lt (__len, __buf,
+					     "confstr called with bigger length than "
+					     "size of destination buffer")
 {
   return __glibc_fortify (confstr, __len, sizeof (char),
 			  __glibc_objsize (__buf),
@@ -109,8 +142,13 @@ __NTH (confstr (int __name, char *__buf, size_t __len))
 }
 
 
-__fortify_function int
-__NTH (getgroups (int __size, __gid_t __list[]))
+__fortify_function __attribute_overloadable__ int
+__NTH (getgroups (int __size,
+		  __fortify_clang_overload_arg (__gid_t *, ,  __list)))
+     __fortify_clang_warning_only_if_bos_lt (__size * sizeof (__gid_t), __list,
+					     "getgroups called with bigger group "
+					     "count than what can fit into "
+					     "destination buffer")
 {
   return __glibc_fortify (getgroups, __size, sizeof (__gid_t),
 			  __glibc_objsize (__list),
@@ -118,8 +156,13 @@ __NTH (getgroups (int __size, __gid_t __list[]))
 }
 
 
-__fortify_function int
-__NTH (ttyname_r (int __fd, char *__buf, size_t __buflen))
+__fortify_function __attribute_overloadable__ int
+__NTH (ttyname_r (int __fd,
+		 __fortify_clang_overload_arg (char *, ,__buf),
+		 size_t __buflen))
+     __fortify_clang_warning_only_if_bos_lt (__buflen, __buf,
+					     "ttyname_r called with bigger buflen "
+					     "than size of destination buffer")
 {
   return __glibc_fortify (ttyname_r, __buflen, sizeof (char),
 			  __glibc_objsize (__buf),
@@ -128,8 +171,11 @@ __NTH (ttyname_r (int __fd, char *__buf, size_t __buflen))
 
 
 #ifdef __USE_POSIX199506
-__fortify_function int
-getlogin_r (char *__buf, size_t __buflen)
+__fortify_function __attribute_overloadable__ int
+getlogin_r (__fortify_clang_overload_arg (char *, ,__buf), size_t __buflen)
+     __fortify_clang_warning_only_if_bos_lt (__buflen, __buf,
+					     "getlogin_r called with bigger buflen "
+					     "than size of destination buffer")
 {
   return __glibc_fortify (getlogin_r, __buflen, sizeof (char),
 			  __glibc_objsize (__buf),
@@ -139,8 +185,12 @@ getlogin_r (char *__buf, size_t __buflen)
 
 
 #if defined __USE_MISC || defined __USE_UNIX98
-__fortify_function int
-__NTH (gethostname (char *__buf, size_t __buflen))
+__fortify_function __attribute_overloadable__ int
+__NTH (gethostname (__fortify_clang_overload_arg (char *, ,__buf),
+		    size_t __buflen))
+     __fortify_clang_warning_only_if_bos_lt (__buflen, __buf,
+					     "gethostname called with bigger buflen "
+					     "than size of destination buffer")
 {
   return __glibc_fortify (gethostname, __buflen, sizeof (char),
 			  __glibc_objsize (__buf),
@@ -150,8 +200,12 @@ __NTH (gethostname (char *__buf, size_t __buflen))
 
 
 #if defined __USE_MISC || (defined __USE_XOPEN && !defined __USE_UNIX98)
-__fortify_function int
-__NTH (getdomainname (char *__buf, size_t __buflen))
+__fortify_function __attribute_overloadable__ int
+__NTH (getdomainname (__fortify_clang_overload_arg (char *, ,__buf),
+		      size_t __buflen))
+     __fortify_clang_warning_only_if_bos_lt (__buflen, __buf,
+					     "getdomainname called with bigger "
+					     "buflen than size of destination buffer")
 {
   return __glibc_fortify (getdomainname, __buflen, sizeof (char),
 			  __glibc_objsize (__buf),
