diff --git a/include/llvm/Analysis/TargetTransformInfo.h b/include/llvm/Analysis/TargetTransformInfo.h
index 49981416604..11a5b6af097 100644
--- a/include/llvm/Analysis/TargetTransformInfo.h
+++ b/include/llvm/Analysis/TargetTransformInfo.h
@@ -27,6 +27,7 @@
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/DataTypes.h"
+#include <functional>
 
 namespace llvm {