diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 31e4ecb..55ab8dd 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -173,7 +173,7 @@
   bool hadError;
   bool VerifyOnly; // no diagnostics, no structure building
   bool AllowBraceElision;
-  std::map<InitListExpr *, InitListExpr *> SyntacticToSemantic;
+  llvm::DenseMap<InitListExpr *, InitListExpr *> SyntacticToSemantic;
   InitListExpr *FullyStructuredList;
 
   void CheckImplicitInitList(const InitializedEntity &Entity,
@@ -1632,7 +1632,7 @@
 
     // Determine the structural initializer list that corresponds to the
     // current subobject.
-    StructuredList = IsFirstDesignator? SyntacticToSemantic[IList]
+    StructuredList = IsFirstDesignator? SyntacticToSemantic.lookup(IList)
       : getStructuredSubobjectInit(IList, Index, CurrentObjectType,
                                    StructuredList, StructuredIndex,
                                    SourceRange(D->getStartLocation(),
@@ -2046,7 +2046,7 @@
     return 0; // No structured list in verification-only mode.
   Expr *ExistingInit = 0;
   if (!StructuredList)
-    ExistingInit = SyntacticToSemantic[IList];
+    ExistingInit = SyntacticToSemantic.lookup(IList);
   else if (StructuredIndex < StructuredList->getNumInits())
     ExistingInit = StructuredList->getInit(StructuredIndex);