diff --git a/lib/Index/DeclReferenceMap.cpp b/lib/Index/DeclReferenceMap.cpp
new file mode 100644
index 0000000..d6e30ab
--- /dev/null
+++ b/lib/Index/DeclReferenceMap.cpp
@@ -0,0 +1,90 @@
+//===--- DeclReferenceMap.cpp - Map Decls to their references -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  DeclReferenceMap creates a mapping from Decls to the ASTLocations that
+//  reference them.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Index/DeclReferenceMap.h"
+#include "clang/Index/ASTLocation.h"
+#include "ASTVisitor.h"
+using namespace clang;
+using namespace idx;
+
+namespace {
+
+class RefMapper : public ASTVisitor<RefMapper> {
+  DeclReferenceMap::MapTy &Map;
+
+public:
+  RefMapper(DeclReferenceMap::MapTy &map) : Map(map) { }
+
+  void VisitDeclRefExpr(DeclRefExpr *Node);
+  void VisitMemberExpr(MemberExpr *Node);
+  void VisitObjCIvarRefExpr(ObjCIvarRefExpr *Node);
+  
+  void VisitTypedefTypeLoc(TypedefTypeLoc TL);
+  void VisitObjCInterfaceTypeLoc(ObjCInterfaceTypeLoc TL);
+};
+
+} // anonymous namespace
+
+//===----------------------------------------------------------------------===//
+// RefMapper Implementation
+//===----------------------------------------------------------------------===//
+
+void RefMapper::VisitDeclRefExpr(DeclRefExpr *Node) {
+  NamedDecl *PrimD = cast<NamedDecl>(Node->getDecl()->getCanonicalDecl());
+  Map.insert(std::make_pair(PrimD, ASTLocation(CurrentDecl, Node)));
+}
+
+void RefMapper::VisitMemberExpr(MemberExpr *Node) {
+  NamedDecl *PrimD = cast<NamedDecl>(Node->getMemberDecl()->getCanonicalDecl());
+  Map.insert(std::make_pair(PrimD, ASTLocation(CurrentDecl, Node)));
+}
+
+void RefMapper::VisitObjCIvarRefExpr(ObjCIvarRefExpr *Node) {
+  Map.insert(std::make_pair(Node->getDecl(), ASTLocation(CurrentDecl, Node)));
+}
+
+void RefMapper::VisitTypedefTypeLoc(TypedefTypeLoc TL) {
+  NamedDecl *ND = TL.getTypedefDecl();
+  Map.insert(std::make_pair(ND, ASTLocation(CurrentDecl, ND, TL.getNameLoc())));
+}
+
+void RefMapper::VisitObjCInterfaceTypeLoc(ObjCInterfaceTypeLoc TL) {
+  NamedDecl *ND = TL.getIFaceDecl();
+  Map.insert(std::make_pair(ND, ASTLocation(CurrentDecl, ND, TL.getNameLoc())));
+}
+
+//===----------------------------------------------------------------------===//
+// DeclReferenceMap Implementation
+//===----------------------------------------------------------------------===//
+
+DeclReferenceMap::DeclReferenceMap(ASTContext &Ctx) {
+  RefMapper(Map).Visit(Ctx.getTranslationUnitDecl());
+}
+
+DeclReferenceMap::astlocation_iterator
+DeclReferenceMap::refs_begin(NamedDecl *D) const {
+  NamedDecl *Prim = cast<NamedDecl>(D->getCanonicalDecl());
+  return astlocation_iterator(Map.lower_bound(Prim));
+}
+
+DeclReferenceMap::astlocation_iterator
+DeclReferenceMap::refs_end(NamedDecl *D) const {
+  NamedDecl *Prim = cast<NamedDecl>(D->getCanonicalDecl());
+  return astlocation_iterator(Map.upper_bound(Prim));
+}
+
+bool DeclReferenceMap::refs_empty(NamedDecl *D) const {
+  NamedDecl *Prim = cast<NamedDecl>(D->getCanonicalDecl());
+  return refs_begin(Prim) == refs_end(Prim);
+}