diff --git a/lib/Index/DeclReferenceMap.cpp b/lib/Index/DeclReferenceMap.cpp
new file mode 100644
index 0000000..841d7fb
--- /dev/null
+++ b/lib/Index/DeclReferenceMap.cpp
@@ -0,0 +1,132 @@
+//===--- DeclReferenceMap.cpp - Map Decls to their references ---*- C++ -*-===//
+//
+//                     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 "clang/AST/Decl.h"
+#include "clang/AST/Stmt.h"
+#include "clang/AST/DeclVisitor.h"
+#include "clang/AST/StmtVisitor.h"
+#include "llvm/Support/Compiler.h"
+using namespace clang;
+using namespace idx;
+
+namespace {
+
+class VISIBILITY_HIDDEN StmtMapper : public StmtVisitor<StmtMapper> {
+  DeclReferenceMap::MapTy &Map;
+  Decl *Parent;
+
+public:
+  StmtMapper(DeclReferenceMap::MapTy &map, Decl *parent)
+    : Map(map), Parent(parent) { }
+
+  void VisitDeclStmt(DeclStmt *Node);
+  void VisitDeclRefExpr(DeclRefExpr *Node);
+  void VisitStmt(Stmt *Node);
+};
+
+class VISIBILITY_HIDDEN DeclMapper : public DeclVisitor<DeclMapper> {
+  DeclReferenceMap::MapTy &Map;
+  
+public:
+  DeclMapper(DeclReferenceMap::MapTy &map)
+    : Map(map) { }
+
+  void VisitDeclContext(DeclContext *DC);
+  void VisitVarDecl(VarDecl *D);
+  void VisitFunctionDecl(FunctionDecl *D);
+  void VisitBlockDecl(BlockDecl *D);
+  void VisitDecl(Decl *D);
+};
+
+} // anonymous namespace
+
+//===----------------------------------------------------------------------===//
+// StmtMapper Implementation
+//===----------------------------------------------------------------------===//
+
+void StmtMapper::VisitDeclStmt(DeclStmt *Node) {
+  DeclMapper Mapper(Map);
+  for (DeclStmt::decl_iterator
+         I = Node->decl_begin(), E = Node->decl_end(); I != E; ++I)
+    Mapper.Visit(*I);
+}
+
+void StmtMapper::VisitDeclRefExpr(DeclRefExpr *Node) {
+  NamedDecl *PrimD = cast<NamedDecl>(Node->getDecl()->getPrimaryDecl());
+  Map.insert(std::make_pair(PrimD, ASTLocation(Parent, Node)));
+}
+
+void StmtMapper::VisitStmt(Stmt *Node) {
+  for (Stmt::child_iterator
+         I = Node->child_begin(), E = Node->child_end(); I != E; ++I)
+    Visit(*I);
+}
+
+//===----------------------------------------------------------------------===//
+// DeclMapper Implementation
+//===----------------------------------------------------------------------===//
+
+void DeclMapper::VisitDeclContext(DeclContext *DC) {
+  for (DeclContext::decl_iterator
+         I = DC->decls_begin(), E = DC->decls_end(); I != E; ++I)
+    Visit(*I);
+}
+
+void DeclMapper::VisitFunctionDecl(FunctionDecl *D) {
+  if (!D->isThisDeclarationADefinition())
+    return;
+  
+  StmtMapper(Map, D).Visit(D->getBody());
+}
+
+void DeclMapper::VisitBlockDecl(BlockDecl *D) {
+  StmtMapper(Map, D).Visit(D->getBody());
+}
+
+void DeclMapper::VisitVarDecl(VarDecl *D) {
+  if (Expr *Init = D->getInit())
+    StmtMapper(Map, D).Visit(Init);
+}
+
+void DeclMapper::VisitDecl(Decl *D) {
+  if (DeclContext *DC = dyn_cast<DeclContext>(D))
+    VisitDeclContext(DC);
+}
+
+//===----------------------------------------------------------------------===//
+// DeclReferenceMap Implementation
+//===----------------------------------------------------------------------===//
+
+DeclReferenceMap::DeclReferenceMap(ASTContext &Ctx) {
+  DeclMapper(Map).Visit(Ctx.getTranslationUnitDecl());
+}
+
+DeclReferenceMap::astlocation_iterator
+DeclReferenceMap::refs_begin(NamedDecl *D) const {
+  NamedDecl *Prim = cast<NamedDecl>(D->getPrimaryDecl());
+  return astlocation_iterator(Map.lower_bound(Prim));  
+}
+
+DeclReferenceMap::astlocation_iterator
+DeclReferenceMap::refs_end(NamedDecl *D) const {
+  NamedDecl *Prim = cast<NamedDecl>(D->getPrimaryDecl());
+  return astlocation_iterator(Map.upper_bound(Prim));  
+}
+
+bool DeclReferenceMap::refs_empty(NamedDecl *D) const {
+  NamedDecl *Prim = cast<NamedDecl>(D->getPrimaryDecl());
+  return refs_begin(Prim) == refs_end(Prim);  
+}