diff --git a/include/llvm/Pass.h b/include/llvm/Pass.h
index a5c1c61c4bf..e70dfc1c9ab 100644
--- a/include/llvm/Pass.h
+++ b/include/llvm/Pass.h
@@ -36,7 +36,8 @@
 #include <typeinfo>
 #include <cassert>
 
-#define USE_OLD_PASSMANAGER 1
+//Use new Pass Manager. Disable old Pass Manager.
+//#define USE_OLD_PASSMANAGER 1
 
 namespace llvm {