diff --git a/llvm/lib/Transforms/Scalar/ConstantProp.cpp b/llvm/lib/Transforms/Scalar/ConstantProp.cpp
index d78556c00403..d9a297cdf1f4 100644
--- a/llvm/lib/Transforms/Scalar/ConstantProp.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstantProp.cpp
@@ -20,6 +20,7 @@
 
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Constant.h"
 #include "llvm/Instruction.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/InstIterator.h"