diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 5a65d35..9259633 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -1391,12 +1391,15 @@
 AC_CHECK_FUNCS([getpagesize getrusage getrlimit setrlimit gettimeofday ])
 AC_CHECK_FUNCS([isatty mkdtemp mkstemp ])
 AC_CHECK_FUNCS([mktemp posix_spawn realpath sbrk setrlimit strdup ])
-AC_CHECK_FUNCS([strerror strerror_r strerror_s setenv ])
+AC_CHECK_FUNCS([strerror strerror_r setenv ])
 AC_CHECK_FUNCS([strtoll strtoq sysconf malloc_zone_statistics ])
 AC_CHECK_FUNCS([setjmp longjmp sigsetjmp siglongjmp writev])
 AC_C_PRINTF_A
 AC_FUNC_RAND48
 
+dnl Check the declaration "Secure API" on Windows environments.
+AC_CHECK_DECLS([strerror_s])
+
 dnl Check symbols in libgcc.a for JIT on Mingw.
 if test "$llvm_cv_os_type" = "MingW" ; then
   AC_CHECK_LIB(gcc,_alloca,AC_DEFINE([HAVE__ALLOCA],[1],[Have host's _alloca]))
diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index 9e2cbe1..c2fe431 100755
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -149,7 +149,7 @@
 check_symbol_exists(strtoq stdlib.h HAVE_STRTOQ)
 check_symbol_exists(strerror string.h HAVE_STRERROR)
 check_symbol_exists(strerror_r string.h HAVE_STRERROR_R)
-check_symbol_exists(strerror_s string.h HAVE_STRERROR_S)
+check_symbol_exists(strerror_s string.h HAVE_DECL_STRERROR_S)
 check_symbol_exists(memcpy string.h HAVE_MEMCPY)
 check_symbol_exists(memmove string.h HAVE_MEMMOVE)
 check_symbol_exists(setenv stdlib.h HAVE_SETENV)
diff --git a/configure b/configure
index a03bc93..959822f 100755
--- a/configure
+++ b/configure
@@ -18679,8 +18679,7 @@
 
 
 
-
-for ac_func in strerror strerror_r strerror_s setenv
+for ac_func in strerror strerror_r setenv
 do
 as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
 { echo "$as_me:$LINENO: checking for $ac_func" >&5
@@ -19199,6 +19198,93 @@
 fi
 
 
+{ echo "$as_me:$LINENO: checking whether strerror_s is declared" >&5
+echo $ECHO_N "checking whether strerror_s is declared... $ECHO_C" >&6; }
+if test "${ac_cv_have_decl_strerror_s+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+$ac_includes_default
+int
+main ()
+{
+#ifndef strerror_s
+  char *p = (char *) strerror_s;
+  return !p;
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag" || test ! -s conftest.err'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_have_decl_strerror_s=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv_have_decl_strerror_s=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv_have_decl_strerror_s" >&5
+echo "${ECHO_T}$ac_cv_have_decl_strerror_s" >&6; }
+if test $ac_cv_have_decl_strerror_s = yes; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STRERROR_S 1
+_ACEOF
+
+
+else
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_STRERROR_S 0
+_ACEOF
+
+
+fi
+
+
+
 if test "$llvm_cv_os_type" = "MingW" ; then
   { echo "$as_me:$LINENO: checking for _alloca in -lgcc" >&5
 echo $ECHO_N "checking for _alloca in -lgcc... $ECHO_C" >&6; }
diff --git a/include/llvm/Config/config.h.cmake b/include/llvm/Config/config.h.cmake
index 50b369b..bf69375 100644
--- a/include/llvm/Config/config.h.cmake
+++ b/include/llvm/Config/config.h.cmake
@@ -62,6 +62,10 @@
 /* Define to 1 if you have the <ctype.h> header file. */
 #cmakedefine HAVE_CTYPE_H ${HAVE_CTYPE_H}
 
+/* Define to 1 if you have the declaration of `strerror_s', and to 0 if you
+   don't. */
+#cmakedefine01 HAVE_DECL_STRERROR_S
+
 /* Define to 1 if you have the <dirent.h> header file, and it defines `DIR'.
    */
 #cmakedefine HAVE_DIRENT_H ${HAVE_DIRENT_H}
@@ -368,9 +372,6 @@
 /* Define to 1 if you have the `strerror_r' function. */
 #cmakedefine HAVE_STRERROR_R ${HAVE_STRERROR_R}
 
-/* Define to 1 if you have the `strerror_s' function. */
-#cmakedefine HAVE_STRERROR_S ${HAVE_STRERROR_S}
-
 /* Define to 1 if you have the <strings.h> header file. */
 #cmakedefine HAVE_STRINGS_H ${HAVE_STRINGS_H}
 
diff --git a/include/llvm/Config/config.h.in b/include/llvm/Config/config.h.in
index 041010c..14c44b4 100644
--- a/include/llvm/Config/config.h.in
+++ b/include/llvm/Config/config.h.in
@@ -78,6 +78,10 @@
 /* Define to 1 if you have the <ctype.h> header file. */
 #undef HAVE_CTYPE_H
 
+/* Define to 1 if you have the declaration of `strerror_s', and to 0 if you
+   don't. */
+#undef HAVE_DECL_STRERROR_S
+
 /* Define to 1 if you have the <dirent.h> header file, and it defines `DIR'.
    */
 #undef HAVE_DIRENT_H
@@ -384,9 +388,6 @@
 /* Define to 1 if you have the `strerror_r' function. */
 #undef HAVE_STRERROR_R
 
-/* Define to 1 if you have the `strerror_s' function. */
-#undef HAVE_STRERROR_S
-
 /* Define to 1 if you have the <strings.h> header file. */
 #undef HAVE_STRINGS_H
 
diff --git a/lib/Support/Errno.cpp b/lib/Support/Errno.cpp
index 312d91e..18c6581 100644
--- a/lib/Support/Errno.cpp
+++ b/lib/Support/Errno.cpp
@@ -50,7 +50,7 @@
 # else
     strerror_r(errnum,buffer,MaxErrStrLen-1);
 # endif
-#elif defined(HAVE_STRERROR_S)  // Windows.
+#elif HAVE_DECL_STRERROR_S // "Windows Secure API"
     if (errnum)
       strerror_s(buffer, errnum);
 #elif defined(HAVE_STRERROR)