Index: lld/trunk/include/lld/Core/Reproduce.h
===================================================================
--- lld/trunk/include/lld/Core/Reproduce.h
+++ lld/trunk/include/lld/Core/Reproduce.h
@@ -34,9 +34,6 @@
 
 // Returns the string form of the given argument.
 std::string toString(llvm::opt::Arg *Arg);
-
-// Replaces backslashes with slashes if Windows.
-std::string convertToUnixPathSeparator(StringRef S);
 }
 
 #endif
Index: lld/trunk/lib/Core/Reproduce.cpp
===================================================================
--- lld/trunk/lib/Core/Reproduce.cpp
+++ lld/trunk/lib/Core/Reproduce.cpp
@@ -39,7 +39,7 @@
     Res = Root.substr(2);
 
   path::append(Res, path::relative_path(Abs));
-  return convertToUnixPathSeparator(Res);
+  return path::convert_to_slash(Res);
 }
 
 // Quote a given string if it contains a space character.
@@ -64,13 +64,3 @@
     return K + V;
   return K + " " + V;
 }
-
-std::string lld::convertToUnixPathSeparator(StringRef S) {
-#ifdef LLVM_ON_WIN32
-  std::string Ret = S.str();
-  std::replace(Ret.begin(), Ret.end(), '\\', '/');
-  return Ret;
-#else
-  return S;
-#endif
-}
Index: llvm/trunk/include/llvm/Support/Path.h
===================================================================
--- llvm/trunk/include/llvm/Support/Path.h
+++ llvm/trunk/include/llvm/Support/Path.h
@@ -207,6 +207,14 @@
 /// @param path A path that is transformed to native format.
 void native(SmallVectorImpl<char> &path);
 
+/// @brief Replaces backslashes with slashes if Windows.
+///
+/// @param path processed path
+/// @result The result of replacing backslashes with forward slashes if Windows.
+/// On Unix, this function is a no-op because backslashes are valid path
+/// chracters.
+std::string convert_to_slash(StringRef path);
+
 /// @}
 /// @name Lexical Observers
 /// @{
Index: llvm/trunk/lib/Support/Path.cpp
===================================================================
--- llvm/trunk/lib/Support/Path.cpp
+++ llvm/trunk/lib/Support/Path.cpp
@@ -571,6 +571,16 @@
 #endif
 }
 
+std::string convert_to_slash(StringRef path) {
+#ifdef LLVM_ON_WIN32
+  std::string s = path.str();
+  std::replace(s.begin(), s.end(), '\\', '/');
+  return s;
+#else
+  return path;
+#endif
+}
+
 StringRef filename(StringRef path) {
   return *rbegin(path);
 }
Index: llvm/trunk/lib/Support/TarWriter.cpp
===================================================================
--- llvm/trunk/lib/Support/TarWriter.cpp
+++ llvm/trunk/lib/Support/TarWriter.cpp
@@ -26,6 +26,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/Path.h"
 
 using namespace llvm;
 
@@ -147,15 +148,6 @@
   OS << StringRef(reinterpret_cast<char *>(&Hdr), sizeof(Hdr));
 }
 
-// We want to use '/' as a path separator even on Windows.
-// This function canonicalizes a given path.
-static std::string canonicalize(std::string S) {
-#ifdef LLVM_ON_WIN32
-  std::replace(S.begin(), S.end(), '\\', '/');
-#endif
-  return S;
-}
-
 // Creates a TarWriter instance and returns it.
 Expected<std::unique_ptr<TarWriter>> TarWriter::create(StringRef OutputPath,
                                                        StringRef BaseDir) {
@@ -171,7 +163,7 @@
 // Append a given file to an archive.
 void TarWriter::append(StringRef Path, StringRef Data) {
   // Write Path and Data.
-  std::string S = BaseDir + "/" + canonicalize(Path) + "\0";
+  std::string S = BaseDir + "/" + sys::path::convert_to_slash(Path) + "\0";
   if (fitsInUstar(S)) {
     writeUstarHeader(OS, S, Data.size());
   } else {