Index: include/llvm/IR/LegacyPassManagers.h
===================================================================
--- include/llvm/IR/LegacyPassManagers.h
+++ include/llvm/IR/LegacyPassManagers.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/MapVector.h"
 #include "llvm/Pass.h"
 #include <vector>
 
@@ -237,7 +238,7 @@
 
   // Map to keep track of last user of the analysis pass.
   // LastUser->second is the last user of Lastuser->first.
-  DenseMap<Pass *, Pass *> LastUser;
+  MapVector<Pass *, Pass *> LastUser;
 
   // Map to keep track of passes that are last used by a pass.
   // This inverse map is initialized at PM->run() based on