diff --git a/clang/lib/CodeGen/ABIInfo.h b/clang/lib/CodeGen/ABIInfo.h
index ac31dfdaf3e4..c0be60ef53bc 100644
--- a/clang/lib/CodeGen/ABIInfo.h
+++ b/clang/lib/CodeGen/ABIInfo.h
@@ -10,6 +10,7 @@
 #ifndef LLVM_CLANG_LIB_CODEGEN_ABIINFO_H
 #define LLVM_CLANG_LIB_CODEGEN_ABIINFO_H
 
+#include "clang/AST/CharUnits.h"
 #include "clang/AST/Type.h"
 #include "llvm/IR/CallingConv.h"
 #include "llvm/IR/Type.h"