Index: utils/TableGen/CMakeLists.txt
===================================================================
--- utils/TableGen/CMakeLists.txt
+++ utils/TableGen/CMakeLists.txt
@@ -33,4 +33,5 @@
   X86DisassemblerTables.cpp
   X86ModRMFilters.cpp
   X86RecognizableInstr.cpp
+  CTagsEmitter.cpp
   )
Index: utils/TableGen/CTagsEmitter.cpp
===================================================================
--- /dev/null
+++ utils/TableGen/CTagsEmitter.cpp
@@ -0,0 +1,104 @@
+//===- CTagsEmitter.cpp - Generate ctags-compatible index ------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This tablegen backend emits an index of definitions in ctags(1) format.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "ctags-emitter"
+
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/TableGen/Error.h"
+#include "llvm/TableGen/Record.h"
+#include "llvm/TableGen/TableGenBackend.h"
+#include <algorithm>
+#include <string>
+#include <vector>
+using namespace llvm;
+
+namespace llvm {
+extern SourceMgr SrcMgr;
+}
+
+namespace {
+
+class Tag {
+private:
+  const std::string *Id;
+  SMLoc Loc;
+public:
+  Tag(const std::string &Name, const SMLoc Location):
+    Id(&Name), Loc(Location)
+  {}
+  int operator<(const Tag &B) const {
+    return *Id < *B.Id;
+  }
+  void emit(raw_ostream &OS) const {
+    int BufferID = SrcMgr.FindBufferContainingLoc(Loc);
+    MemoryBuffer *CurMB = SrcMgr.getBufferInfo(BufferID).Buffer;
+    const char *BufferName = CurMB->getBufferIdentifier();
+    std::pair<unsigned, unsigned> LineAndColumn = SrcMgr.getLineAndColumn(Loc);
+    OS << *Id << "\t" << BufferName << "\t" << LineAndColumn.first << "\n";
+  }
+};
+
+class CTagsEmitter {
+private:
+  RecordKeeper &Records;
+public:
+  CTagsEmitter(RecordKeeper &R):
+    Records(R)
+  {}
+
+  void run(raw_ostream &OS);
+
+private:
+  static SMLoc locate(const Record *R);
+};
+
+} // End anonymous namespace.
+
+SMLoc CTagsEmitter::locate(const Record *R) {
+  ArrayRef<SMLoc> Locs = R->getLoc();
+  if (Locs.empty()) {
+    SMLoc NullLoc;
+    return NullLoc;
+  }
+  return Locs.front();
+}
+
+void CTagsEmitter::run(raw_ostream &OS) {
+  const std::map<std::string, Record*> &Classes = Records.getClasses();
+  const std::map<std::string, Record*> &Defs = Records.getDefs();
+  std::vector<Tag> Tags;
+  // Collect tags.
+  Tags.reserve(Classes.size() + Defs.size());
+  for (std::map<std::string, Record*>::const_iterator I = Classes.begin(),
+       E = Classes.end(); I != E; ++I)
+    Tags.push_back(Tag(I->first, locate(I->second)));
+  for (std::map<std::string, Record*>::const_iterator I = Defs.begin(),
+        E = Defs.end(); I != E; ++I)
+    Tags.push_back(Tag(I->first, locate(I->second)));
+  // Emit tags.
+  std::sort(Tags.begin(), Tags.end());
+  OS << "!_TAG_FILE_FORMAT\t1\t/original ctags format/\n";
+  OS << "!_TAG_FILE_SORTED\t1\t/0=unsorted, 1=sorted, 2=foldcase/\n";
+  for (std::vector<Tag>::const_iterator I = Tags.begin(), E = Tags.end();
+       I != E; ++I)
+    I->emit(OS);
+}
+
+namespace llvm {
+
+void EmitCTags(RecordKeeper &RK, raw_ostream &OS) {
+  CTagsEmitter(RK).run(OS);
+}
+
+} // End llvm namespace.
Index: utils/TableGen/TableGen.cpp
===================================================================
--- utils/TableGen/TableGen.cpp
+++ utils/TableGen/TableGen.cpp
@@ -40,7 +40,8 @@
   GenTgtIntrinsic,
   PrintEnums,
   PrintSets,
-  GenOptParserDefs
+  GenOptParserDefs,
+  GenCTags
 };
 
 namespace {
@@ -82,6 +83,8 @@
                                "Print expanded sets for testing DAG exprs"),
                     clEnumValN(GenOptParserDefs, "gen-opt-parser-defs",
                                "Generate option definitions"),
+                    clEnumValN(GenCTags, "gen-ctags",
+                               "Generate ctags-compatible index"),
                     clEnumValEnd));
 
   cl::opt<std::string>
@@ -161,6 +164,9 @@
     }
     break;
   }
+  case GenCTags:
+    EmitCTags(Records, OS);
+    break;
   }
 
   return false;
Index: utils/TableGen/TableGenBackends.h
===================================================================
--- utils/TableGen/TableGenBackends.h
+++ utils/TableGen/TableGenBackends.h
@@ -75,5 +75,6 @@
 void EmitSubtarget(RecordKeeper &RK, raw_ostream &OS);
 void EmitMapTable(RecordKeeper &RK, raw_ostream &OS);
 void EmitOptParser(RecordKeeper &RK, raw_ostream &OS);
+void EmitCTags(RecordKeeper &RK, raw_ostream &OS);
 
 } // End llvm namespace