diff --git a/tools/llvm-mc/AsmLexer.cpp b/tools/llvm-mc/AsmLexer.cpp
index 578eec18526..4a68d0d354c 100644
--- a/tools/llvm-mc/AsmLexer.cpp
+++ b/tools/llvm-mc/AsmLexer.cpp
@@ -15,6 +15,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include <cerrno>
+#include <cstdlib>
 using namespace llvm;
 
 AsmLexer::AsmLexer(SourceMgr &SM) : SrcMgr(SM) {