diff --git a/llvm/autoconf/configure.ac b/llvm/autoconf/configure.ac
index 464336e31235..0e9e31810e7e 100644
--- a/llvm/autoconf/configure.ac
+++ b/llvm/autoconf/configure.ac
@@ -233,7 +233,7 @@ AC_HEADER_STDC
 AC_HEADER_SYS_WAIT
 
 dnl Checks for POSIX and other various system-specific header files
-AC_CHECK_HEADERS(fcntl.h limits.h sys/time.h unistd.h malloc.h sys/mman.h sys/resource.h dlfcn.h link.h execinfo.h)
+AC_CHECK_HEADERS(fcntl.h limits.h sys/time.h unistd.h malloc.h sys/mman.h sys/resource.h dlfcn.h link.h execinfo.h windows.h)
 
 dnl Check for things that need to be included in public headers, and so
 dnl for which we may not have access to a HAVE_* preprocessor #define.
diff --git a/llvm/configure b/llvm/configure
index e2721f125dd8..bc51db023062 100755
--- a/llvm/configure
+++ b/llvm/configure
@@ -18917,7 +18917,8 @@ fi
 
 
 
-for ac_header in fcntl.h limits.h sys/time.h unistd.h malloc.h sys/mman.h sys/resource.h dlfcn.h link.h execinfo.h
+
+for ac_header in fcntl.h limits.h sys/time.h unistd.h malloc.h sys/mman.h sys/resource.h dlfcn.h link.h execinfo.h windows.h
 do
 as_ac_Header=`echo "ac_cv_header_$ac_header" | $as_tr_sh`
 if eval "test \"\${$as_ac_Header+set}\" = set"; then
diff --git a/llvm/include/Config/config.h.in b/llvm/include/Config/config.h.in
index 9f35aca69839..1b396fea834f 100644
--- a/llvm/include/Config/config.h.in
+++ b/llvm/include/Config/config.h.in
@@ -131,6 +131,9 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #undef HAVE_UNISTD_H
 
+/* Define to have the <windows.h> header file. */
+#undef HAVE_WINDOWS_H
+
 /* Define to the address where bug reports for this package should be sent. */
 #undef PACKAGE_BUGREPORT