diff --git a/clang/lib/Frontend/DependencyFile.cpp b/clang/lib/Frontend/DependencyFile.cpp
new file mode 100644
index 0000000..4cee280
--- /dev/null
+++ b/clang/lib/Frontend/DependencyFile.cpp
@@ -0,0 +1,171 @@
+//===--- DependencyFile.cpp - Generate dependency file --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This code generates dependency files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Frontend/Utils.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/PPCallbacks.h"
+#include "clang/Lex/DirectoryLookup.h"
+#include "clang/Basic/SourceLocation.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/System/Path.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/raw_ostream.h"
+#include <string>
+
+using namespace clang;
+
+namespace {
+class VISIBILITY_HIDDEN DependencyFileCallback : public PPCallbacks {
+  std::vector<std::string> Files;
+  llvm::StringSet<> FilesSet;
+  const Preprocessor *PP;
+  std::vector<std::string> Targets;
+  llvm::raw_ostream *OS;
+  bool IncludeSystemHeaders;
+  bool PhonyTarget;
+private:
+  bool FileMatchesDepCriteria(const char *Filename,
+                              SrcMgr::CharacteristicKind FileType);
+  void OutputDependencyFile();
+
+public:
+  DependencyFileCallback(const Preprocessor *_PP, 
+                         llvm::raw_ostream *_OS, 
+                         const std::vector<std::string> &_Targets,
+                         bool _IncludeSystemHeaders,
+                         bool _PhonyTarget)
+    : PP(_PP), Targets(_Targets), OS(_OS),
+      IncludeSystemHeaders(_IncludeSystemHeaders), PhonyTarget(_PhonyTarget) {}
+
+  ~DependencyFileCallback() {
+    OutputDependencyFile();
+    OS->flush();
+    delete OS;
+  }
+
+  virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
+                           SrcMgr::CharacteristicKind FileType);
+};
+}
+
+
+
+void clang::AttachDependencyFileGen(Preprocessor *PP, llvm::raw_ostream *OS,
+                                    std::vector<std::string> &Targets,
+                                    bool IncludeSystemHeaders,
+                                    bool PhonyTarget) {
+  assert(!Targets.empty() && "Target required for dependency generation");
+
+  DependencyFileCallback *PPDep = 
+    new DependencyFileCallback(PP, OS, Targets, IncludeSystemHeaders, 
+                               PhonyTarget);
+  PP->setPPCallbacks(PPDep);
+}
+
+/// FileMatchesDepCriteria - Determine whether the given Filename should be
+/// considered as a dependency.
+bool DependencyFileCallback::FileMatchesDepCriteria(const char *Filename,
+                                          SrcMgr::CharacteristicKind FileType) {
+  if (strcmp("<built-in>", Filename) == 0)
+    return false;
+
+  if (IncludeSystemHeaders)
+    return true;
+
+  return FileType == SrcMgr::C_User;
+}
+
+void DependencyFileCallback::FileChanged(SourceLocation Loc,
+                                         FileChangeReason Reason,
+                                         SrcMgr::CharacteristicKind FileType) {
+  if (Reason != PPCallbacks::EnterFile)
+    return;
+  
+  // Dependency generation really does want to go all the way to the
+  // file entry for a source location to find out what is depended on.
+  // We do not want #line markers to affect dependency generation!
+  SourceManager &SM = PP->getSourceManager();
+  
+  const FileEntry *FE =
+    SM.getFileEntryForID(SM.getFileID(SM.getInstantiationLoc(Loc)));
+  if (FE == 0) return;
+  
+  const char *Filename = FE->getName();
+  if (!FileMatchesDepCriteria(Filename, FileType))
+    return;
+
+  // Remove leading "./"
+  if (Filename[0] == '.' && Filename[1] == '/')
+    Filename = &Filename[2];
+
+  if (FilesSet.insert(Filename))
+    Files.push_back(Filename);
+}
+
+void DependencyFileCallback::OutputDependencyFile() {
+  // Write out the dependency targets, trying to avoid overly long
+  // lines when possible. We try our best to emit exactly the same
+  // dependency file as GCC (4.2), assuming the included files are the
+  // same.
+  const unsigned MaxColumns = 75;
+  unsigned Columns = 0;
+
+  for (std::vector<std::string>::iterator
+         I = Targets.begin(), E = Targets.end(); I != E; ++I) {
+    unsigned N = I->length();
+    if (Columns == 0) {
+      Columns += N;
+      *OS << *I;
+    } else if (Columns + N + 2 > MaxColumns) {
+      Columns = N + 2;
+      *OS << " \\\n  " << *I;
+    } else {
+      Columns += N + 1;
+      *OS << ' ' << *I;
+    }
+  }
+
+  *OS << ':';
+  Columns += 1;
+  
+  // Now add each dependency in the order it was seen, but avoiding
+  // duplicates.
+  for (std::vector<std::string>::iterator I = Files.begin(),
+         E = Files.end(); I != E; ++I) {
+    // Start a new line if this would exceed the column limit. Make
+    // sure to leave space for a trailing " \" in case we need to
+    // break the line on the next iteration.
+    unsigned N = I->length();
+    if (Columns + (N + 1) + 2 > MaxColumns) {
+      *OS << " \\\n ";
+      Columns = 2;
+    }
+    *OS << ' ' << *I;
+    Columns += N + 1;
+  }
+  *OS << '\n';
+
+  // Create phony targets if requested.
+  if (PhonyTarget) {
+    // Skip the first entry, this is always the input file itself.
+    for (std::vector<std::string>::iterator I = Files.begin() + 1,
+           E = Files.end(); I != E; ++I) {
+      *OS << '\n';
+      *OS << *I << ":\n";
+    }
+  }
+}
+