diff --git a/lib/Frontend/InitHeaderSearch.cpp b/lib/Frontend/InitHeaderSearch.cpp
new file mode 100644
index 0000000..85287dd
--- /dev/null
+++ b/lib/Frontend/InitHeaderSearch.cpp
@@ -0,0 +1,754 @@
+//===--- InitHeaderSearch.cpp - Initialize header search paths ----------*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the InitHeaderSearch class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Frontend/Utils.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Frontend/HeaderSearchOptions.h"
+#include "clang/Lex/HeaderSearch.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/System/Path.h"
+#include "llvm/Config/config.h"
+#ifdef _MSC_VER
+  #define WIN32_LEAN_AND_MEAN 1
+  #include <windows.h>
+#endif
+using namespace clang;
+using namespace clang::frontend;
+
+namespace {
+
+/// InitHeaderSearch - This class makes it easier to set the search paths of
+///  a HeaderSearch object. InitHeaderSearch stores several search path lists
+///  internally, which can be sent to a HeaderSearch object in one swoop.
+class InitHeaderSearch {
+  std::vector<DirectoryLookup> IncludeGroup[4];
+  HeaderSearch& Headers;
+  bool Verbose;
+  std::string isysroot;
+
+public:
+
+  InitHeaderSearch(HeaderSearch &HS,
+      bool verbose = false, const std::string &iSysroot = "")
+    : Headers(HS), Verbose(verbose), isysroot(iSysroot) {}
+
+  /// AddPath - Add the specified path to the specified group list.
+  void AddPath(const llvm::Twine &Path, IncludeDirGroup Group,
+               bool isCXXAware, bool isUserSupplied,
+               bool isFramework, bool IgnoreSysRoot = false);
+
+  /// AddGnuCPlusPlusIncludePaths - Add the necessary paths to suport a gnu
+  ///  libstdc++.
+  void AddGnuCPlusPlusIncludePaths(llvm::StringRef Base,
+                                   llvm::StringRef ArchDir,
+                                   llvm::StringRef Dir32,
+                                   llvm::StringRef Dir64,
+                                   const llvm::Triple &triple);
+
+  /// AddMinGWCPlusPlusIncludePaths - Add the necessary paths to suport a MinGW
+  ///  libstdc++.
+  void AddMinGWCPlusPlusIncludePaths(llvm::StringRef Base,
+                                     llvm::StringRef Arch,
+                                     llvm::StringRef Version);
+
+  /// AddDelimitedPaths - Add a list of paths delimited by the system PATH
+  /// separator. The processing follows that of the CPATH variable for gcc.
+  void AddDelimitedPaths(llvm::StringRef String);
+
+  // AddDefaultCIncludePaths - Add paths that should always be searched.
+  void AddDefaultCIncludePaths(const llvm::Triple &triple);
+
+  // AddDefaultCPlusPlusIncludePaths -  Add paths that should be searched when
+  //  compiling c++.
+  void AddDefaultCPlusPlusIncludePaths(const llvm::Triple &triple);
+
+  /// AddDefaultSystemIncludePaths - Adds the default system include paths so
+  ///  that e.g. stdio.h is found.
+  void AddDefaultSystemIncludePaths(const LangOptions &Lang,
+                                    const llvm::Triple &triple);
+
+  /// Realize - Merges all search path lists into one list and send it to
+  /// HeaderSearch.
+  void Realize();
+};
+
+}
+
+void InitHeaderSearch::AddPath(const llvm::Twine &Path,
+                               IncludeDirGroup Group, bool isCXXAware,
+                               bool isUserSupplied, bool isFramework,
+                               bool IgnoreSysRoot) {
+  assert(!Path.isTriviallyEmpty() && "can't handle empty path here");
+  FileManager &FM = Headers.getFileMgr();
+
+  // Compute the actual path, taking into consideration -isysroot.
+  llvm::SmallString<256> MappedPathStr;
+  llvm::raw_svector_ostream MappedPath(MappedPathStr);
+
+  // Handle isysroot.
+  if (Group == System && !IgnoreSysRoot) {
+    // FIXME: Portability.  This should be a sys::Path interface, this doesn't
+    // handle things like C:\ right, nor win32 \\network\device\blah.
+    if (isysroot.size() != 1 || isysroot[0] != '/') // Add isysroot if present.
+      MappedPath << isysroot;
+  }
+
+  Path.print(MappedPath);
+
+  // Compute the DirectoryLookup type.
+  SrcMgr::CharacteristicKind Type;
+  if (Group == Quoted || Group == Angled)
+    Type = SrcMgr::C_User;
+  else if (isCXXAware)
+    Type = SrcMgr::C_System;
+  else
+    Type = SrcMgr::C_ExternCSystem;
+
+
+  // If the directory exists, add it.
+  if (const DirectoryEntry *DE = FM.getDirectory(MappedPath.str())) {
+    IncludeGroup[Group].push_back(DirectoryLookup(DE, Type, isUserSupplied,
+                                                  isFramework));
+    return;
+  }
+
+  // Check to see if this is an apple-style headermap (which are not allowed to
+  // be frameworks).
+  if (!isFramework) {
+    if (const FileEntry *FE = FM.getFile(MappedPath.str())) {
+      if (const HeaderMap *HM = Headers.CreateHeaderMap(FE)) {
+        // It is a headermap, add it to the search path.
+        IncludeGroup[Group].push_back(DirectoryLookup(HM, Type,isUserSupplied));
+        return;
+      }
+    }
+  }
+
+  if (Verbose)
+    llvm::errs() << "ignoring nonexistent directory \""
+                 << MappedPath.str() << "\"\n";
+}
+
+
+void InitHeaderSearch::AddDelimitedPaths(llvm::StringRef at) {
+  if (at.empty()) // Empty string should not add '.' path.
+    return;
+
+  llvm::StringRef::size_type delim;
+  while ((delim = at.find(llvm::sys::PathSeparator)) != llvm::StringRef::npos) {
+    if (delim == 0)
+      AddPath(".", Angled, false, true, false);
+    else
+      AddPath(at.substr(0, delim), Angled, false, true, false);
+    at = at.substr(delim + 1);
+  }
+
+  if (at.empty())
+    AddPath(".", Angled, false, true, false);
+  else
+    AddPath(at, Angled, false, true, false);
+}
+
+void InitHeaderSearch::AddGnuCPlusPlusIncludePaths(llvm::StringRef Base,
+                                                   llvm::StringRef ArchDir,
+                                                   llvm::StringRef Dir32,
+                                                   llvm::StringRef Dir64,
+                                                   const llvm::Triple &triple) {
+  // Add the base dir
+  AddPath(Base, System, true, false, false);
+
+  // Add the multilib dirs
+  llvm::Triple::ArchType arch = triple.getArch();
+  bool is64bit = arch == llvm::Triple::ppc64 || arch == llvm::Triple::x86_64;
+  if (is64bit)
+    AddPath(Base + "/" + ArchDir + "/" + Dir64, System, true, false, false);
+  else
+    AddPath(Base + "/" + ArchDir + "/" + Dir32, System, true, false, false);
+
+  // Add the backward dir
+  AddPath(Base + "/backward", System, true, false, false);
+}
+
+void InitHeaderSearch::AddMinGWCPlusPlusIncludePaths(llvm::StringRef Base,
+                                                     llvm::StringRef Arch,
+                                                     llvm::StringRef Version) {
+  AddPath(Base + "/" + Arch + "/" + Version + "/include",
+          System, true, false, false);
+  AddPath(Base + "/" + Arch + "/" + Version + "/include/c++",
+          System, true, false, false);
+  AddPath(Base + "/" + Arch + "/" + Version + "/include/c++/backward",
+          System, true, false, false);
+}
+
+  // FIXME: This probably should goto to some platform utils place.
+#ifdef _MSC_VER
+
+  // Read registry string.
+  // This also supports a means to look for high-versioned keys by use
+  // of a $VERSION placeholder in the key path.
+  // $VERSION in the key path is a placeholder for the version number,
+  // causing the highest value path to be searched for and used.
+  // I.e. "HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\VisualStudio\\$VERSION".
+  // There can be additional characters in the component.  Only the numberic
+  // characters are compared.
+static bool getSystemRegistryString(const char *keyPath, const char *valueName,
+                                    char *value, size_t maxLength) {
+  HKEY hRootKey = NULL;
+  HKEY hKey = NULL;
+  const char* subKey = NULL;
+  DWORD valueType;
+  DWORD valueSize = maxLength - 1;
+  long lResult;
+  bool returnValue = false;
+  if (strncmp(keyPath, "HKEY_CLASSES_ROOT\\", 18) == 0) {
+    hRootKey = HKEY_CLASSES_ROOT;
+    subKey = keyPath + 18;
+  }
+  else if (strncmp(keyPath, "HKEY_USERS\\", 11) == 0) {
+    hRootKey = HKEY_USERS;
+    subKey = keyPath + 11;
+  }
+  else if (strncmp(keyPath, "HKEY_LOCAL_MACHINE\\", 19) == 0) {
+    hRootKey = HKEY_LOCAL_MACHINE;
+    subKey = keyPath + 19;
+  }
+  else if (strncmp(keyPath, "HKEY_CURRENT_USER\\", 18) == 0) {
+    hRootKey = HKEY_CURRENT_USER;
+    subKey = keyPath + 18;
+  }
+  else
+    return(false);
+  const char *placeHolder = strstr(subKey, "$VERSION");
+  char bestName[256];
+  bestName[0] = '\0';
+  // If we have a $VERSION placeholder, do the highest-version search.
+  if (placeHolder) {
+    const char *keyEnd = placeHolder - 1;
+    const char *nextKey = placeHolder;
+    // Find end of previous key.
+    while ((keyEnd > subKey) && (*keyEnd != '\\'))
+      keyEnd--;
+    // Find end of key containing $VERSION.
+    while (*nextKey && (*nextKey != '\\'))
+      nextKey++;
+    size_t partialKeyLength = keyEnd - subKey;
+    char partialKey[256];
+    if (partialKeyLength > sizeof(partialKey))
+      partialKeyLength = sizeof(partialKey);
+    strncpy(partialKey, subKey, partialKeyLength);
+    partialKey[partialKeyLength] = '\0';
+    HKEY hTopKey = NULL;
+    lResult = RegOpenKeyEx(hRootKey, partialKey, 0, KEY_READ, &hTopKey);
+    if (lResult == ERROR_SUCCESS) {
+      char keyName[256];
+      int bestIndex = -1;
+      double bestValue = 0.0;
+      DWORD index, size = sizeof(keyName) - 1;
+      for (index = 0; RegEnumKeyEx(hTopKey, index, keyName, &size, NULL,
+          NULL, NULL, NULL) == ERROR_SUCCESS; index++) {
+        const char *sp = keyName;
+        while (*sp && !isdigit(*sp))
+          sp++;
+        if (!*sp)
+          continue;
+        const char *ep = sp + 1;
+        while (*ep && (isdigit(*ep) || (*ep == '.')))
+          ep++;
+        char numBuf[32];
+        strncpy(numBuf, sp, sizeof(numBuf) - 1);
+        numBuf[sizeof(numBuf) - 1] = '\0';
+        double value = strtod(numBuf, NULL);
+        if (value > bestValue) {
+          bestIndex = (int)index;
+          bestValue = value;
+          strcpy(bestName, keyName);
+        }
+        size = sizeof(keyName) - 1;
+      }
+      // If we found the highest versioned key, open the key and get the value.
+      if (bestIndex != -1) {
+        // Append rest of key.
+        strncat(bestName, nextKey, sizeof(bestName) - 1);
+        bestName[sizeof(bestName) - 1] = '\0';
+        // Open the chosen key path remainder.
+        lResult = RegOpenKeyEx(hTopKey, bestName, 0, KEY_READ, &hKey);
+        if (lResult == ERROR_SUCCESS) {
+          lResult = RegQueryValueEx(hKey, valueName, NULL, &valueType,
+            (LPBYTE)value, &valueSize);
+          if (lResult == ERROR_SUCCESS)
+            returnValue = true;
+          RegCloseKey(hKey);
+        }
+      }
+      RegCloseKey(hTopKey);
+    }
+  }
+  else {
+    lResult = RegOpenKeyEx(hRootKey, subKey, 0, KEY_READ, &hKey);
+    if (lResult == ERROR_SUCCESS) {
+      lResult = RegQueryValueEx(hKey, valueName, NULL, &valueType,
+        (LPBYTE)value, &valueSize);
+      if (lResult == ERROR_SUCCESS)
+        returnValue = true;
+      RegCloseKey(hKey);
+    }
+  }
+  return(returnValue);
+}
+#else // _MSC_VER
+  // Read registry string.
+static bool getSystemRegistryString(const char*, const char*, char*, size_t) {
+  return(false);
+}
+#endif // _MSC_VER
+
+  // Get Visual Studio installation directory.
+static bool getVisualStudioDir(std::string &path) {
+  char vsIDEInstallDir[256];
+  // Try the Windows registry first.
+  bool hasVCDir = getSystemRegistryString(
+    "HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\VisualStudio\\$VERSION",
+    "InstallDir", vsIDEInstallDir, sizeof(vsIDEInstallDir) - 1);
+    // If we have both vc80 and vc90, pick version we were compiled with. 
+  if (hasVCDir && vsIDEInstallDir[0]) {
+    char *p = (char*)strstr(vsIDEInstallDir, "\\Common7\\IDE");
+    if (p)
+      *p = '\0';
+    path = vsIDEInstallDir;
+    return(true);
+  }
+  else {
+    // Try the environment.
+    const char* vs90comntools = getenv("VS90COMNTOOLS");
+    const char* vs80comntools = getenv("VS80COMNTOOLS");
+    const char* vscomntools = NULL;
+      // If we have both vc80 and vc90, pick version we were compiled with. 
+    if (vs90comntools && vs80comntools) {
+      #if (_MSC_VER >= 1500)  // VC90
+          vscomntools = vs90comntools;
+      #elif (_MSC_VER == 1400) // VC80
+          vscomntools = vs80comntools;
+      #else
+          vscomntools = vs90comntools;
+      #endif
+    }
+    else if (vs90comntools)
+      vscomntools = vs90comntools;
+    else if (vs80comntools)
+      vscomntools = vs80comntools;
+    if (vscomntools && *vscomntools) {
+      char *p = (char*)strstr(vscomntools, "\\Common7\\Tools");
+      if (p)
+        *p = '\0';
+      path = vscomntools;
+      return(true);
+    }
+    else
+      return(false);
+  }
+  return(false);
+}
+
+  // Get Windows SDK installation directory.
+static bool getWindowsSDKDir(std::string &path) {
+  char windowsSDKInstallDir[256];
+  // Try the Windows registry.
+  bool hasSDKDir = getSystemRegistryString(
+   "HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Microsoft SDKs\\Windows\\$VERSION",
+    "InstallationFolder", windowsSDKInstallDir, sizeof(windowsSDKInstallDir) - 1);
+    // If we have both vc80 and vc90, pick version we were compiled with. 
+  if (hasSDKDir && windowsSDKInstallDir[0]) {
+    path = windowsSDKInstallDir;
+    return(true);
+  }
+  return(false);
+}
+
+void InitHeaderSearch::AddDefaultCIncludePaths(const llvm::Triple &triple) {
+  // FIXME: temporary hack: hard-coded paths.
+  llvm::StringRef CIncludeDirs(C_INCLUDE_DIRS);
+  if (CIncludeDirs != "") {
+    llvm::SmallVector<llvm::StringRef, 5> dirs;
+    CIncludeDirs.split(dirs, ":");
+    for (llvm::SmallVectorImpl<llvm::StringRef>::iterator i = dirs.begin();
+         i != dirs.end();
+         ++i) 
+      AddPath(*i, System, false, false, false);
+    return;
+  }
+  llvm::Triple::OSType os = triple.getOS();
+  switch (os) {
+  case llvm::Triple::Win32:
+    {
+      std::string VSDir;
+      std::string WindowsSDKDir;
+      if (getVisualStudioDir(VSDir)) {
+        AddPath(VSDir + "\\VC\\include", System, false, false, false);
+        if (getWindowsSDKDir(WindowsSDKDir))
+          AddPath(WindowsSDKDir, System, false, false, false);
+        else
+          AddPath(VSDir + "\\VC\\PlatformSDK\\Include",
+            System, false, false, false);
+      }
+      else {
+          // Default install paths.
+        AddPath("C:/Program Files/Microsoft Visual Studio 9.0/VC/include",
+          System, false, false, false);
+        AddPath(
+        "C:/Program Files/Microsoft Visual Studio 9.0/VC/PlatformSDK/Include",
+          System, false, false, false);
+        AddPath("C:/Program Files/Microsoft Visual Studio 8/VC/include",
+          System, false, false, false);
+        AddPath(
+        "C:/Program Files/Microsoft Visual Studio 8/VC/PlatformSDK/Include",
+          System, false, false, false);
+          // For some clang developers.
+        AddPath("G:/Program Files/Microsoft Visual Studio 9.0/VC/include",
+          System, false, false, false);
+        AddPath(
+        "G:/Program Files/Microsoft Visual Studio 9.0/VC/PlatformSDK/Include",
+          System, false, false, false);
+      }
+    }
+    break;
+  case llvm::Triple::MinGW64:
+  case llvm::Triple::MinGW32:
+    AddPath("c:/mingw/include", System, true, false, false);
+    break;
+  default:
+    break;
+  }
+
+  AddPath("/usr/local/include", System, false, false, false);
+  AddPath("/usr/include", System, false, false, false);
+}
+
+void InitHeaderSearch::AddDefaultCPlusPlusIncludePaths(const llvm::Triple &triple) {
+  llvm::Triple::OSType os = triple.getOS();
+  llvm::StringRef CxxIncludeRoot(CXX_INCLUDE_ROOT);
+  if (CxxIncludeRoot != "") {
+    llvm::StringRef CxxIncludeArch(CXX_INCLUDE_ARCH);
+    if (CxxIncludeArch == "")
+      AddGnuCPlusPlusIncludePaths(CxxIncludeRoot, triple.str().c_str(),
+                                  CXX_INCLUDE_32BIT_DIR, CXX_INCLUDE_64BIT_DIR, triple);
+    else
+      AddGnuCPlusPlusIncludePaths(CxxIncludeRoot, CXX_INCLUDE_ARCH,
+                                  CXX_INCLUDE_32BIT_DIR, CXX_INCLUDE_64BIT_DIR, triple);
+    return;
+  }
+  // FIXME: temporary hack: hard-coded paths.
+  switch (os) {
+  case llvm::Triple::Cygwin:
+    AddPath("/lib/gcc/i686-pc-cygwin/3.4.4/include",
+        System, true, false, false);
+    AddPath("/lib/gcc/i686-pc-cygwin/3.4.4/include/c++",
+        System, true, false, false);
+    break;
+  case llvm::Triple::MinGW64:
+    // Try gcc 4.4.0
+    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw64", "4.4.0");
+    // Try gcc 4.3.0
+    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw64", "4.3.0");
+    // Fall through.
+  case llvm::Triple::MinGW32:
+    // Try gcc 4.4.0
+    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw32", "4.4.0");
+    // Try gcc 4.3.0
+    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw32", "4.3.0");
+    break;
+  case llvm::Triple::Darwin:
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2.1",
+                                "i686-apple-darwin10", "", "x86_64", triple);
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.0.0",
+                                "i686-apple-darwin8", "", "", triple);
+    break;
+  case llvm::Triple::DragonFly:
+    AddPath("/usr/include/c++/4.1", System, true, false, false);
+    break;
+  case llvm::Triple::Linux:
+    // Exherbo (2010-01-25)
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.4.3",
+                                "x86_64-pc-linux-gnu", "32", "", triple);
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.4.3",
+                                "i686-pc-linux-gnu", "", "", triple);
+    // Debian sid
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.4.2",
+                                "x86_64-linux-gnu", "32", "", triple);
+    // Ubuntu 7.10 - Gutsy Gibbon
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.1.3",
+                                "i486-linux-gnu", "", "", triple);
+    // Ubuntu 9.04
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3.3",
+                                "x86_64-linux-gnu","32", "", triple);
+    // Ubuntu 9.10
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.4.1",
+                                "x86_64-linux-gnu", "32", "", triple);
+    // Fedora 8
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.1.2",
+                                "i386-redhat-linux", "", "", triple);
+    // Fedora 9
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3.0",
+                                "i386-redhat-linux", "", "", triple);
+    // Fedora 10
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3.2",
+                                "i386-redhat-linux","", "", triple);
+
+    // Fedora 10 x86_64
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3.2",
+                                "x86_64-redhat-linux", "32", "", triple);
+
+    // Fedora 11
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.4.1",
+                                "i586-redhat-linux","", "", triple);
+
+    // Fedora 12
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.4.2",
+                                "i686-redhat-linux","", "", triple);
+
+    // openSUSE 11.1 32 bit
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3",
+                                "i586-suse-linux", "", "", triple);
+    // openSUSE 11.1 64 bit
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3",
+                                "x86_64-suse-linux", "32", "", triple);
+    // openSUSE 11.2
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.4",
+                                "i586-suse-linux", "", "", triple);
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.4",
+                                "x86_64-suse-linux", "", "", triple);
+    // Arch Linux 2008-06-24
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3.1",
+                                "i686-pc-linux-gnu", "", "", triple);
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3.1",
+                                "x86_64-unknown-linux-gnu", "", "", triple);
+    // Gentoo x86 2009.1 stable
+    AddGnuCPlusPlusIncludePaths(
+      "/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4",
+      "i686-pc-linux-gnu", "", "", triple);
+    // Gentoo x86 2009.0 stable
+    AddGnuCPlusPlusIncludePaths(
+      "/usr/lib/gcc/i686-pc-linux-gnu/4.3.2/include/g++-v4",
+      "i686-pc-linux-gnu", "", "", triple);
+    // Gentoo x86 2008.0 stable
+    AddGnuCPlusPlusIncludePaths(
+      "/usr/lib/gcc/i686-pc-linux-gnu/4.1.2/include/g++-v4",
+      "i686-pc-linux-gnu", "", "", triple);
+    // Ubuntu 8.10
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3",
+                                "i486-pc-linux-gnu", "", "", triple);
+    // Ubuntu 9.04
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.3",
+                                "i486-linux-gnu","", "", triple);
+    // Gentoo amd64 stable
+    AddGnuCPlusPlusIncludePaths(
+        "/usr/lib/gcc/x86_64-pc-linux-gnu/4.1.2/include/g++-v4",
+        "i686-pc-linux-gnu", "", "", triple);
+    break;
+  case llvm::Triple::FreeBSD:
+    AddGnuCPlusPlusIncludePaths("/usr/include/c++/4.2", "", "", "", triple);
+    break;
+  case llvm::Triple::Solaris:
+    // Solaris - Fall though..
+  case llvm::Triple::AuroraUX:
+    // AuroraUX
+    AddGnuCPlusPlusIncludePaths("/opt/gcc4/include/c++/4.2.4",
+                                "i386-pc-solaris2.11", "", "", triple);
+    break;
+  default:
+    break;
+  }
+}
+
+void InitHeaderSearch::AddDefaultSystemIncludePaths(const LangOptions &Lang,
+                                                    const llvm::Triple &triple) {
+  if (Lang.CPlusPlus)
+    AddDefaultCPlusPlusIncludePaths(triple);
+
+  AddDefaultCIncludePaths(triple);
+
+  // Add the default framework include paths on Darwin.
+  if (triple.getOS() == llvm::Triple::Darwin) {
+    AddPath("/System/Library/Frameworks", System, true, false, true);
+    AddPath("/Library/Frameworks", System, true, false, true);
+  }
+}
+
+/// RemoveDuplicates - If there are duplicate directory entries in the specified
+/// search list, remove the later (dead) ones.
+static void RemoveDuplicates(std::vector<DirectoryLookup> &SearchList,
+                             bool Verbose) {
+  llvm::SmallPtrSet<const DirectoryEntry *, 8> SeenDirs;
+  llvm::SmallPtrSet<const DirectoryEntry *, 8> SeenFrameworkDirs;
+  llvm::SmallPtrSet<const HeaderMap *, 8> SeenHeaderMaps;
+  for (unsigned i = 0; i != SearchList.size(); ++i) {
+    unsigned DirToRemove = i;
+
+    const DirectoryLookup &CurEntry = SearchList[i];
+
+    if (CurEntry.isNormalDir()) {
+      // If this isn't the first time we've seen this dir, remove it.
+      if (SeenDirs.insert(CurEntry.getDir()))
+        continue;
+    } else if (CurEntry.isFramework()) {
+      // If this isn't the first time we've seen this framework dir, remove it.
+      if (SeenFrameworkDirs.insert(CurEntry.getFrameworkDir()))
+        continue;
+    } else {
+      assert(CurEntry.isHeaderMap() && "Not a headermap or normal dir?");
+      // If this isn't the first time we've seen this headermap, remove it.
+      if (SeenHeaderMaps.insert(CurEntry.getHeaderMap()))
+        continue;
+    }
+
+    // If we have a normal #include dir/framework/headermap that is shadowed
+    // later in the chain by a system include location, we actually want to
+    // ignore the user's request and drop the user dir... keeping the system
+    // dir.  This is weird, but required to emulate GCC's search path correctly.
+    //
+    // Since dupes of system dirs are rare, just rescan to find the original
+    // that we're nuking instead of using a DenseMap.
+    if (CurEntry.getDirCharacteristic() != SrcMgr::C_User) {
+      // Find the dir that this is the same of.
+      unsigned FirstDir;
+      for (FirstDir = 0; ; ++FirstDir) {
+        assert(FirstDir != i && "Didn't find dupe?");
+
+        const DirectoryLookup &SearchEntry = SearchList[FirstDir];
+
+        // If these are different lookup types, then they can't be the dupe.
+        if (SearchEntry.getLookupType() != CurEntry.getLookupType())
+          continue;
+
+        bool isSame;
+        if (CurEntry.isNormalDir())
+          isSame = SearchEntry.getDir() == CurEntry.getDir();
+        else if (CurEntry.isFramework())
+          isSame = SearchEntry.getFrameworkDir() == CurEntry.getFrameworkDir();
+        else {
+          assert(CurEntry.isHeaderMap() && "Not a headermap or normal dir?");
+          isSame = SearchEntry.getHeaderMap() == CurEntry.getHeaderMap();
+        }
+
+        if (isSame)
+          break;
+      }
+
+      // If the first dir in the search path is a non-system dir, zap it
+      // instead of the system one.
+      if (SearchList[FirstDir].getDirCharacteristic() == SrcMgr::C_User)
+        DirToRemove = FirstDir;
+    }
+
+    if (Verbose) {
+      llvm::errs() << "ignoring duplicate directory \""
+                   << CurEntry.getName() << "\"\n";
+      if (DirToRemove != i)
+        llvm::errs() << "  as it is a non-system directory that duplicates "
+                     << "a system directory\n";
+    }
+
+    // This is reached if the current entry is a duplicate.  Remove the
+    // DirToRemove (usually the current dir).
+    SearchList.erase(SearchList.begin()+DirToRemove);
+    --i;
+  }
+}
+
+
+void InitHeaderSearch::Realize() {
+  // Concatenate ANGLE+SYSTEM+AFTER chains together into SearchList.
+  std::vector<DirectoryLookup> SearchList;
+  SearchList = IncludeGroup[Angled];
+  SearchList.insert(SearchList.end(), IncludeGroup[System].begin(),
+                    IncludeGroup[System].end());
+  SearchList.insert(SearchList.end(), IncludeGroup[After].begin(),
+                    IncludeGroup[After].end());
+  RemoveDuplicates(SearchList, Verbose);
+  RemoveDuplicates(IncludeGroup[Quoted], Verbose);
+
+  // Prepend QUOTED list on the search list.
+  SearchList.insert(SearchList.begin(), IncludeGroup[Quoted].begin(),
+                    IncludeGroup[Quoted].end());
+
+
+  bool DontSearchCurDir = false;  // TODO: set to true if -I- is set?
+  Headers.SetSearchPaths(SearchList, IncludeGroup[Quoted].size(),
+                         DontSearchCurDir);
+
+  // If verbose, print the list of directories that will be searched.
+  if (Verbose) {
+    llvm::errs() << "#include \"...\" search starts here:\n";
+    unsigned QuotedIdx = IncludeGroup[Quoted].size();
+    for (unsigned i = 0, e = SearchList.size(); i != e; ++i) {
+      if (i == QuotedIdx)
+        llvm::errs() << "#include <...> search starts here:\n";
+      const char *Name = SearchList[i].getName();
+      const char *Suffix;
+      if (SearchList[i].isNormalDir())
+        Suffix = "";
+      else if (SearchList[i].isFramework())
+        Suffix = " (framework directory)";
+      else {
+        assert(SearchList[i].isHeaderMap() && "Unknown DirectoryLookup");
+        Suffix = " (headermap)";
+      }
+      llvm::errs() << " " << Name << Suffix << "\n";
+    }
+    llvm::errs() << "End of search list.\n";
+  }
+}
+
+void clang::ApplyHeaderSearchOptions(HeaderSearch &HS,
+                                     const HeaderSearchOptions &HSOpts,
+                                     const LangOptions &Lang,
+                                     const llvm::Triple &Triple) {
+  InitHeaderSearch Init(HS, HSOpts.Verbose, HSOpts.Sysroot);
+
+  // Add the user defined entries.
+  for (unsigned i = 0, e = HSOpts.UserEntries.size(); i != e; ++i) {
+    const HeaderSearchOptions::Entry &E = HSOpts.UserEntries[i];
+    Init.AddPath(E.Path, E.Group, false, E.IsUserSupplied, E.IsFramework,
+                 false);
+  }
+
+  // Add entries from CPATH and friends.
+  Init.AddDelimitedPaths(HSOpts.EnvIncPath);
+  if (Lang.CPlusPlus && Lang.ObjC1)
+    Init.AddDelimitedPaths(HSOpts.ObjCXXEnvIncPath);
+  else if (Lang.CPlusPlus)
+    Init.AddDelimitedPaths(HSOpts.CXXEnvIncPath);
+  else if (Lang.ObjC1)
+    Init.AddDelimitedPaths(HSOpts.ObjCEnvIncPath);
+  else
+    Init.AddDelimitedPaths(HSOpts.CEnvIncPath);
+
+  if (HSOpts.UseBuiltinIncludes) {
+    // Ignore the sys root, we *always* look for clang headers relative to
+    // supplied path.
+    llvm::sys::Path P(HSOpts.ResourceDir);
+    P.appendComponent("include");
+    Init.AddPath(P.str(), System, false, false, false, /*IgnoreSysRoot=*/ true);
+  }
+
+  if (HSOpts.UseStandardIncludes)
+    Init.AddDefaultSystemIncludePaths(Lang, Triple);
+
+  Init.Realize();
+}