diff --git a/lib/Frontend/FixItRewriter.cpp b/lib/Frontend/FixItRewriter.cpp
new file mode 100644
index 0000000..a53d1e5
--- /dev/null
+++ b/lib/Frontend/FixItRewriter.cpp
@@ -0,0 +1,140 @@
+//===--- FixItRewriter.cpp - Fix-It Rewriter Diagnostic Client --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This is a diagnostic client adaptor that performs rewrites as
+// suggested by code modification hints attached to diagnostics. It
+// then forwards any diagnostics to the adapted diagnostic client.
+//
+//===----------------------------------------------------------------------===//
+#include "clang/Basic/SourceManager.h"
+#include "clang/Frontend/FixItRewriter.h"
+#include "clang/Rewrite/Rewriter.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/System/Path.h"
+#include <cstdio>
+using namespace clang;
+
+FixItRewriter::FixItRewriter(DiagnosticClient *Client, 
+                             SourceManager &SourceMgr)
+  : Client(Client), NumFailures(0) {
+  Rewrite = new Rewriter(SourceMgr);
+}
+
+FixItRewriter::~FixItRewriter() {
+  delete Rewrite;
+}
+
+bool FixItRewriter::WriteFixedFile(const std::string &InFileName, 
+                                   const std::string &OutFileName) {
+  if (NumFailures > 0) {
+    // FIXME: Use diagnostic machinery!
+    std::fprintf(stderr, 
+                 "%d fix-it failures detected; code will not be modified",
+                 NumFailures);
+    return true;
+  }
+
+  llvm::OwningPtr<llvm::raw_ostream> OwnedStream;
+  llvm::raw_ostream *OutFile;
+  if (OutFileName == "-") {
+    OutFile = &llvm::outs();
+  } else if (!OutFileName.empty()) {
+    std::string Err;
+    OutFile = new llvm::raw_fd_ostream(OutFileName.c_str(), 
+                                       // set binary mode (critical for Windoze)
+                                       true, 
+                                       Err);
+    OwnedStream.reset(OutFile);
+  } else if (InFileName == "-") {
+    OutFile = &llvm::outs();
+  } else {
+    llvm::sys::Path Path(InFileName);
+    Path.eraseSuffix();
+    Path.appendSuffix("cpp");
+    std::string Err;
+    OutFile = new llvm::raw_fd_ostream(Path.toString().c_str(), 
+                                       // set binary mode (critical for Windoze)
+                                       true, 
+                                       Err);
+    OwnedStream.reset(OutFile);
+  }  
+
+  FileID MainFileID = Rewrite->getSourceMgr().getMainFileID();
+  if (const RewriteBuffer *RewriteBuf = 
+        Rewrite->getRewriteBufferFor(MainFileID)) {
+    *OutFile << std::string(RewriteBuf->begin(), RewriteBuf->end());
+  } else {
+    std::fprintf(stderr, "Main file is unchanged\n");
+  }
+  OutFile->flush();
+
+  return false;
+}
+
+bool FixItRewriter::IncludeInDiagnosticCounts() const {
+  return Client? Client->IncludeInDiagnosticCounts() : false;
+}
+
+void FixItRewriter::HandleDiagnostic(Diagnostic::Level DiagLevel,
+                                     const DiagnosticInfo &Info) {
+  if (Client)
+    Client->HandleDiagnostic(DiagLevel, Info);
+
+  // Make sure that we can perform all of the modifications we
+  // in this diagnostic.
+  bool CanRewrite = true;
+  for (unsigned Idx = 0; Idx < Info.getNumCodeModificationHints(); ++Idx) {
+    const CodeModificationHint &Hint = Info.getCodeModificationHint(Idx);
+    if (Hint.RemoveRange.isValid() &&
+        (!Rewrite->isRewritable(Hint.RemoveRange.getBegin()) ||
+         !Rewrite->isRewritable(Hint.RemoveRange.getEnd()) ||
+         Rewrite->getRangeSize(Hint.RemoveRange) == -1)) {
+      CanRewrite = false;
+      break;
+    }
+
+    if (Hint.InsertionLoc.isValid() && 
+        !Rewrite->isRewritable(Hint.InsertionLoc)) {
+      CanRewrite = false;
+      break;
+    }
+  }
+
+  if (!CanRewrite) // FIXME: warn the user that this rewrite couldn't be done
+    return;
+
+  bool Failed = false;
+  for (unsigned Idx = 0; Idx < Info.getNumCodeModificationHints(); ++Idx) {
+    const CodeModificationHint &Hint = Info.getCodeModificationHint(Idx);
+    if (Hint.RemoveRange.isValid()) {
+      if (Hint.CodeToInsert.empty()) {
+        // We're removing code.
+        if (Rewrite->RemoveText(Hint.RemoveRange.getBegin(),
+                                Rewrite->getRangeSize(Hint.RemoveRange)))
+          Failed = true;
+      } else {
+        // We're replacing code.
+        if (Rewrite->ReplaceText(Hint.RemoveRange.getBegin(),
+                                 Rewrite->getRangeSize(Hint.RemoveRange),
+                                 Hint.CodeToInsert.c_str(),
+                                 Hint.CodeToInsert.size()))
+          Failed = true;
+      }
+    } else {
+      // We're adding code.
+      if (Rewrite->InsertStrBefore(Hint.InsertionLoc, Hint.CodeToInsert))
+        Failed = true;
+    }
+  }
+
+  if (Failed)
+    ++NumFailures;
+}