diff --git a/lib/Support/CommandLine.cpp b/lib/Support/CommandLine.cpp
index 3454ffc00fe..2337e2e2558 100644
--- a/lib/Support/CommandLine.cpp
+++ b/lib/Support/CommandLine.cpp
@@ -23,6 +23,7 @@
 #include <iostream>
 #include <cstdlib>
 #include <cerrno>
+#include <cstring>
 using namespace llvm;
 
 using namespace cl;