diff --git a/include/llvm/CodeGen/LiveStackAnalysis.h b/include/llvm/CodeGen/LiveStackAnalysis.h
index 3da33ba3fc9..f495507c66e 100644
--- a/include/llvm/CodeGen/LiveStackAnalysis.h
+++ b/include/llvm/CodeGen/LiveStackAnalysis.h
@@ -21,6 +21,7 @@
 #include "llvm/Support/Allocator.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include <map>
+#include <unordered_map>
 
 namespace llvm {