diff --git a/include/clang/Basic/FileManager.h b/include/clang/Basic/FileManager.h
index d0e0118..e71f51a 100644
--- a/include/clang/Basic/FileManager.h
+++ b/include/clang/Basic/FileManager.h
@@ -189,7 +189,7 @@
   /// getDirectory - Lookup, cache, and verify the specified directory.  This
   /// returns null if the directory doesn't exist.
   ///
-  const DirectoryEntry *getDirectory(const llvm::StringRef &Filename) {
+  const DirectoryEntry *getDirectory(llvm::StringRef Filename) {
     return getDirectory(Filename.begin(), Filename.end());
   }
   const DirectoryEntry *getDirectory(const char *FileStart,const char *FileEnd);
@@ -197,7 +197,7 @@
   /// getFile - Lookup, cache, and verify the specified file.  This returns null
   /// if the file doesn't exist.
   ///
-  const FileEntry *getFile(const llvm::StringRef &Filename) {
+  const FileEntry *getFile(llvm::StringRef Filename) {
     return getFile(Filename.begin(), Filename.end());
   }
   const FileEntry *getFile(const char *FilenameStart,
@@ -206,8 +206,8 @@
   /// \brief Retrieve a file entry for a "virtual" file that acts as
   /// if there were a file with the given name on disk. The file
   /// itself is not accessed.
-  const FileEntry *getVirtualFile(const llvm::StringRef &Filename,
-                                  off_t Size, time_t ModificationTime);
+  const FileEntry *getVirtualFile(llvm::StringRef Filename, off_t Size,
+                                  time_t ModificationTime);
   void PrintStats() const;
 };
 
diff --git a/include/clang/Rewrite/Rewriter.h b/include/clang/Rewrite/Rewriter.h
index 0612a15..b3d4035 100644
--- a/include/clang/Rewrite/Rewriter.h
+++ b/include/clang/Rewrite/Rewriter.h
@@ -64,7 +64,7 @@
   /// the buffer is specified relative to the original SourceBuffer.  The
   /// text is inserted after the specified location.
   ///
-  void InsertText(unsigned OrigOffset, const llvm::StringRef &Str,
+  void InsertText(unsigned OrigOffset, llvm::StringRef Str,
                   bool InsertAfter = true);
 
 
@@ -72,14 +72,14 @@
   /// offset in the buffer is specified relative to the original
   /// SourceBuffer. The text is inserted before the specified location.  This is
   /// method is the same as InsertText with "InsertAfter == false".
-  void InsertTextBefore(unsigned OrigOffset, const llvm::StringRef &Str) {
+  void InsertTextBefore(unsigned OrigOffset, llvm::StringRef Str) {
     InsertText(OrigOffset, Str, false);
   }
 
   /// InsertTextAfter - Insert some text at the specified point, where the
   /// offset in the buffer is specified relative to the original SourceBuffer.
   /// The text is inserted after the specified location.
-  void InsertTextAfter(unsigned OrigOffset, const llvm::StringRef &Str) {
+  void InsertTextAfter(unsigned OrigOffset, llvm::StringRef Str) {
     InsertText(OrigOffset, Str);
   }
 
@@ -87,7 +87,7 @@
   /// buffer with a new string.  This is effectively a combined "remove/insert"
   /// operation.
   void ReplaceText(unsigned OrigOffset, unsigned OrigLength,
-                   const llvm::StringRef &NewStr);
+                   llvm::StringRef NewStr);
 
 private:  // Methods only usable by Rewriter.
 
@@ -164,7 +164,7 @@
   /// InsertText - Insert the specified string at the specified location in the
   /// original buffer.  This method returns true (and does nothing) if the input
   /// location was not rewritable, false otherwise.
-  bool InsertText(SourceLocation Loc, const llvm::StringRef &Str,
+  bool InsertText(SourceLocation Loc, llvm::StringRef Str,
                   bool InsertAfter = true);
 
   /// InsertTextAfter - Insert the specified string at the specified location in
@@ -172,7 +172,7 @@
   ///  the input location was not rewritable, false otherwise.  Text is
   ///  inserted after any other text that has been previously inserted
   ///  at the some point (the default behavior for InsertText).
-  bool InsertTextAfter(SourceLocation Loc, const llvm::StringRef &Str) {
+  bool InsertTextAfter(SourceLocation Loc, llvm::StringRef Str) {
     return InsertText(Loc, Str);
   }
 
@@ -181,7 +181,7 @@
   /// location was not rewritable, false otherwise.  Text is
   /// inserted before any other text that has been previously inserted
   /// at the some point.
-  bool InsertTextBefore(SourceLocation Loc, const llvm::StringRef &Str) {
+  bool InsertTextBefore(SourceLocation Loc, llvm::StringRef Str) {
     return InsertText(Loc, Str, false);
   }
 
@@ -192,7 +192,7 @@
   /// buffer with a new string.  This is effectively a combined "remove/insert"
   /// operation.
   bool ReplaceText(SourceLocation Start, unsigned OrigLength,
-                   const llvm::StringRef &NewStr);
+                   llvm::StringRef NewStr);
 
   /// ReplaceStmt - This replaces a Stmt/Expr with another, using the pretty
   /// printer to generate the replacement code.  This returns true if the input
diff --git a/lib/Basic/FileManager.cpp b/lib/Basic/FileManager.cpp
index c4296c3..3c91a0f 100644
--- a/lib/Basic/FileManager.cpp
+++ b/lib/Basic/FileManager.cpp
@@ -331,8 +331,8 @@
 }
 
 const FileEntry *
-FileManager::getVirtualFile(const llvm::StringRef &Filename,
-                            off_t Size, time_t ModificationTime) {
+FileManager::getVirtualFile(llvm::StringRef Filename, off_t Size,
+                            time_t ModificationTime) {
   const char *NameStart = Filename.begin(), *NameEnd = Filename.end();
 
   ++NumFileLookups;
diff --git a/lib/Checker/LLVMConventionsChecker.cpp b/lib/Checker/LLVMConventionsChecker.cpp
index 0576f08..c121257 100644
--- a/lib/Checker/LLVMConventionsChecker.cpp
+++ b/lib/Checker/LLVMConventionsChecker.cpp
@@ -36,7 +36,7 @@
 
 /// Check whether the declaration is semantically inside the top-level
 /// namespace named by ns.
-static bool InNamespace(const Decl *D, const llvm::StringRef &NS) {
+static bool InNamespace(const Decl *D, llvm::StringRef NS) {
   const DeclContext *DC = D->getDeclContext();
   const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(D->getDeclContext());
   if (!ND)
diff --git a/lib/Frontend/PCHReader.cpp b/lib/Frontend/PCHReader.cpp
index 56b77b1..70a9a06 100644
--- a/lib/Frontend/PCHReader.cpp
+++ b/lib/Frontend/PCHReader.cpp
@@ -141,7 +141,7 @@
 }
 
 struct EmptyStringRef {
-  bool operator ()(const llvm::StringRef &r) const { return r.empty(); }
+  bool operator ()(llvm::StringRef r) const { return r.empty(); }
 };
 struct EmptyBlock {
   bool operator ()(const PCHPredefinesBlock &r) const { return r.Data.empty(); }
diff --git a/lib/Rewrite/Rewriter.cpp b/lib/Rewrite/Rewriter.cpp
index 8b0bf91..92e2b03 100644
--- a/lib/Rewrite/Rewriter.cpp
+++ b/lib/Rewrite/Rewriter.cpp
@@ -40,7 +40,7 @@
   AddReplaceDelta(OrigOffset, -Size);
 }
 
-void RewriteBuffer::InsertText(unsigned OrigOffset, const llvm::StringRef &Str,
+void RewriteBuffer::InsertText(unsigned OrigOffset, llvm::StringRef Str,
                                bool InsertAfter) {
 
   // Nothing to insert, exit early.
@@ -57,7 +57,7 @@
 /// buffer with a new string.  This is effectively a combined "remove+insert"
 /// operation.
 void RewriteBuffer::ReplaceText(unsigned OrigOffset, unsigned OrigLength,
-                                const llvm::StringRef &NewStr) {
+                                llvm::StringRef NewStr) {
   unsigned RealOffset = getMappedOffset(OrigOffset, true);
   Buffer.erase(RealOffset, OrigLength);
   Buffer.insert(RealOffset, NewStr.begin(), NewStr.end());
@@ -185,7 +185,7 @@
 
 /// InsertText - Insert the specified string at the specified location in the
 /// original buffer.
-bool Rewriter::InsertText(SourceLocation Loc, const llvm::StringRef &Str,
+bool Rewriter::InsertText(SourceLocation Loc, llvm::StringRef Str,
                           bool InsertAfter) {
   if (!isRewritable(Loc)) return true;
   FileID FID;
@@ -207,7 +207,7 @@
 /// buffer with a new string.  This is effectively a combined "remove/insert"
 /// operation.
 bool Rewriter::ReplaceText(SourceLocation Start, unsigned OrigLength,
-                           const llvm::StringRef &NewStr) {
+                           llvm::StringRef NewStr) {
   if (!isRewritable(Start)) return true;
   FileID StartFileID;
   unsigned StartOffs = getLocationOffsetAndFileID(Start, StartFileID);