diff --git a/toolchain/musl/patches/040-Add-format-attribute-to-some-function-declarations.patch b/toolchain/musl/patches/040-Add-format-attribute-to-some-function-declarations.patch
new file mode 100644
index 0000000000..1d61d92ff3
--- /dev/null
+++ b/toolchain/musl/patches/040-Add-format-attribute-to-some-function-declarations.patch
@@ -0,0 +1,209 @@
+From e6683d001a95d7c3d4d992496f00f77e01fcd268 Mon Sep 17 00:00:00 2001
+From: Hauke Mehrtens <hauke@hauke-m.de>
+Date: Sun, 22 Nov 2015 15:04:23 +0100
+Subject: [PATCH v2] Add format attribute to some function declarations
+
+GCC and Clang are able to check the format arguments given to a
+function and warn the user if there is a error in the format arguments
+or if there is a potential uncontrolled format string security problem
+in the code. GCC does this automatically for some functions like
+printf(), but it is also possible to annotate other functions in a way
+that it will check them too. This feature is used by glibc for many
+functions. This patch adds the attribute to the some functions of musl
+expect for these functions where gcc automatically adds it.
+
+GCC automatically adds checks for these functions: printf, fprintf,
+sprintf, scanf, fscanf, sscanf, strftime, vprintf, vfprintf and
+vsprintf.
+
+The documentation from gcc is here:
+https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
+
+The documentation from Clang is here:
+http://clang.llvm.org/docs/AttributeReference.html#format-gnu-format
+
+Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
+---
+ include/err.h      | 26 +++++++++++++++++---------
+ include/monetary.h | 12 ++++++++++--
+ include/stdio.h    | 29 ++++++++++++++++++++---------
+ include/syslog.h   | 12 ++++++++++--
+ 4 files changed, 57 insertions(+), 22 deletions(-)
+
+diff --git a/include/err.h b/include/err.h
+index 9f5cb6b..a5e3cde 100644
+--- a/include/err.h
++++ b/include/err.h
+@@ -8,15 +8,23 @@
+ extern "C" {
+ #endif
+ 
+-void warn(const char *, ...);
+-void vwarn(const char *, va_list);
+-void warnx(const char *, ...);
+-void vwarnx(const char *, va_list);
+-
+-_Noreturn void err(int, const char *, ...);
+-_Noreturn void verr(int, const char *, va_list);
+-_Noreturn void errx(int, const char *, ...);
+-_Noreturn void verrx(int, const char *, va_list);
++#if __GNUC__ >= 3
++#define __fp(x, y) __attribute__ ((__format__ (__printf__, x, y)))
++#else
++#define __fp(x, y)
++#endif
++
++void warn(const char *, ...) __fp(1, 2);
++void vwarn(const char *, va_list) __fp(1, 0);
++void warnx(const char *, ...) __fp(1, 2);
++void vwarnx(const char *, va_list) __fp(1, 0);
++
++_Noreturn void err(int, const char *, ...) __fp(2, 3);
++_Noreturn void verr(int, const char *, va_list) __fp(2, 0);
++_Noreturn void errx(int, const char *, ...) __fp(2, 3);
++_Noreturn void verrx(int, const char *, va_list) __fp(2, 0);
++
++#undef __fp
+ 
+ #ifdef __cplusplus
+ }
+diff --git a/include/monetary.h b/include/monetary.h
+index a91fa56..85c4d23 100644
+--- a/include/monetary.h
++++ b/include/monetary.h
+@@ -13,8 +13,16 @@ extern "C" {
+ 
+ #include <bits/alltypes.h>
+ 
+-ssize_t strfmon(char *__restrict, size_t, const char *__restrict, ...);
+-ssize_t strfmon_l(char *__restrict, size_t, locale_t, const char *__restrict, ...);
++#if __GNUC__ >= 3
++#define __fsfm(x, y) __attribute__ ((__format__ (__strfmon__, x, y)))
++#else
++#define __fsfm(x, y)
++#endif
++
++ssize_t strfmon(char *__restrict, size_t, const char *__restrict, ...) __fsfm(3, 4);
++ssize_t strfmon_l(char *__restrict, size_t, locale_t, const char *__restrict, ...) __fsfm(4, 5);
++
++#undef __fsfm
+ 
+ #ifdef __cplusplus
+ }
+diff --git a/include/stdio.h b/include/stdio.h
+index 884d2e6..17ca68e 100644
+--- a/include/stdio.h
++++ b/include/stdio.h
+@@ -21,6 +21,14 @@ extern "C" {
+ 
+ #include <bits/alltypes.h>
+ 
++#if __GNUC__ >= 3
++#define __fp(x, y) __attribute__ ((__format__ (__printf__, x, y)))
++#define __fs(x, y) __attribute__ ((__format__ (__scanf__, x, y)))
++#else
++#define __fp(x, y)
++#define __fs(x, y)
++#endif
++
+ #ifdef __cplusplus
+ #define NULL 0L
+ #else
+@@ -102,19 +110,19 @@ int puts(const char *);
+ int printf(const char *__restrict, ...);
+ int fprintf(FILE *__restrict, const char *__restrict, ...);
+ int sprintf(char *__restrict, const char *__restrict, ...);
+-int snprintf(char *__restrict, size_t, const char *__restrict, ...);
++int snprintf(char *__restrict, size_t, const char *__restrict, ...) __fp(3, 4);
+ 
+ int vprintf(const char *__restrict, __isoc_va_list);
+ int vfprintf(FILE *__restrict, const char *__restrict, __isoc_va_list);
+ int vsprintf(char *__restrict, const char *__restrict, __isoc_va_list);
+-int vsnprintf(char *__restrict, size_t, const char *__restrict, __isoc_va_list);
++int vsnprintf(char *__restrict, size_t, const char *__restrict, __isoc_va_list) __fp(3, 0);
+ 
+ int scanf(const char *__restrict, ...);
+ int fscanf(FILE *__restrict, const char *__restrict, ...);
+ int sscanf(const char *__restrict, const char *__restrict, ...);
+-int vscanf(const char *__restrict, __isoc_va_list);
+-int vfscanf(FILE *__restrict, const char *__restrict, __isoc_va_list);
+-int vsscanf(const char *__restrict, const char *__restrict, __isoc_va_list);
++int vscanf(const char *__restrict, __isoc_va_list) __fs(1, 0);
++int vfscanf(FILE *__restrict, const char *__restrict, __isoc_va_list) __fs(2, 0);
++int vsscanf(const char *__restrict, const char *__restrict, __isoc_va_list) __fs(2, 0);
+ 
+ void perror(const char *);
+ 
+@@ -135,8 +143,8 @@ int pclose(FILE *);
+ int fileno(FILE *);
+ int fseeko(FILE *, off_t, int);
+ off_t ftello(FILE *);
+-int dprintf(int, const char *__restrict, ...);
+-int vdprintf(int, const char *__restrict, __isoc_va_list);
++int dprintf(int, const char *__restrict, ...) __fp(2, 3);
++int vdprintf(int, const char *__restrict, __isoc_va_list) __fp(2, 0);
+ void flockfile(FILE *);
+ int ftrylockfile(FILE *);
+ void funlockfile(FILE *);
+@@ -175,8 +183,8 @@ int fileno_unlocked(FILE *);
+ int getw(FILE *);
+ int putw(int, FILE *);
+ char *fgetln(FILE *, size_t *);
+-int asprintf(char **, const char *, ...);
+-int vasprintf(char **, const char *, __isoc_va_list);
++int asprintf(char **, const char *, ...) __fp(2, 3);
++int vasprintf(char **, const char *, __isoc_va_list) __fp(2, 0);
+ #endif
+ 
+ #ifdef _GNU_SOURCE
+@@ -184,6 +192,9 @@ char *fgets_unlocked(char *, int, FILE *);
+ int fputs_unlocked(const char *, FILE *);
+ #endif
+ 
++#undef __fp
++#undef __fs
++
+ #if defined(_LARGEFILE64_SOURCE) || defined(_GNU_SOURCE)
+ #define tmpfile64 tmpfile
+ #define fopen64 fopen
+diff --git a/include/syslog.h b/include/syslog.h
+index 5b4d296..33b549d 100644
+--- a/include/syslog.h
++++ b/include/syslog.h
+@@ -56,16 +56,22 @@ extern "C" {
+ #define LOG_NOWAIT 0x10
+ #define LOG_PERROR 0x20
+ 
++#if __GNUC__ >= 3
++#define __fp(x, y) __attribute__ ((__format__ (__printf__, x, y)))
++#else
++#define __fp(x, y)
++#endif
++
+ void closelog (void);
+ void openlog (const char *, int, int);
+ int setlogmask (int);
+-void syslog (int, const char *, ...);
++void syslog (int, const char *, ...) __fp(2, 3);
+ 
+ #if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+ #define _PATH_LOG "/dev/log"
+ #define __NEED_va_list
+ #include <bits/alltypes.h>
+-void vsyslog (int, const char *, va_list);
++void vsyslog (int, const char *, va_list) __fp(2, 0);
+ #if defined(SYSLOG_NAMES)
+ #define	INTERNAL_NOPRI 0x10
+ #define	INTERNAL_MARK (LOG_NFACILITIES<<3)
+@@ -93,6 +99,8 @@ typedef struct {
+ #endif
+ #endif
+ 
++#undef __fp
++
+ #ifdef __cplusplus
+ }
+ #endif
+-- 
+2.7.0.rc3
+