diff --git a/include/Config/unistd.h b/include/Config/unistd.h
index e9ca783e83d..847db7a3c6e 100644
--- a/include/Config/unistd.h
+++ b/include/Config/unistd.h
@@ -16,12 +16,13 @@
 
 #include "Config/config.h"
 
-#ifdef HAVE_UNISTD_H
+#if defined(HAVE_UNISTD_H) && !defined(_MSC_VER)
 #include <unistd.h>
 #endif
 
 #ifdef _WIN32
 #include <process.h>
+#include <io.h>
 #endif
 
 #endif
diff --git a/include/llvm/Config/unistd.h b/include/llvm/Config/unistd.h
index e9ca783e83d..847db7a3c6e 100644
--- a/include/llvm/Config/unistd.h
+++ b/include/llvm/Config/unistd.h
@@ -16,12 +16,13 @@
 
 #include "Config/config.h"
 
-#ifdef HAVE_UNISTD_H
+#if defined(HAVE_UNISTD_H) && !defined(_MSC_VER)
 #include <unistd.h>
 #endif
 
 #ifdef _WIN32
 #include <process.h>
+#include <io.h>
 #endif
 
 #endif