diff --git a/include/llvm/Support/CodeGenCWrappers.h b/include/llvm/Support/CodeGenCWrappers.h
index eef102fc1fe..97c203ca35c 100644
--- a/include/llvm/Support/CodeGenCWrappers.h
+++ b/include/llvm/Support/CodeGenCWrappers.h
@@ -17,6 +17,7 @@
 #define LLVM_SUPPORT_CODEGENCWRAPPERS_H
 
 #include "llvm-c/TargetMachine.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Support/ErrorHandling.h"