diff --git a/llvm/lib/TableGen/TGLexer.cpp b/llvm/lib/TableGen/TGLexer.cpp
index 0977b00e8c9a..c9c674c8898d 100644
--- a/llvm/lib/TableGen/TGLexer.cpp
+++ b/llvm/lib/TableGen/TGLexer.cpp
@@ -22,6 +22,9 @@
 #include <cstdlib>
 #include <cstring>
 #include <cerrno>
+
+#include "llvm/Config/config.h"
+
 using namespace llvm;
 
 TGLexer::TGLexer(SourceMgr &SM) : SrcMgr(SM) {