diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 8eae7b2..993cdbf 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -728,7 +728,7 @@
 /// EmitString - Emit a string with quotes and a null terminator.
 /// Special characters are emitted properly.
 /// \literal (Eg. '\t') \endliteral
-void AsmPrinter::EmitString(const std::string &String) const {
+void AsmPrinter::EmitString(const StringRef String) const {
   EmitString(String.data(), String.size());
 }
 
diff --git a/lib/CodeGen/AsmPrinter/DIE.h b/lib/CodeGen/AsmPrinter/DIE.h
index d073da7..dc6a70a 100644
--- a/lib/CodeGen/AsmPrinter/DIE.h
+++ b/lib/CodeGen/AsmPrinter/DIE.h
@@ -277,9 +277,9 @@
   /// DIEString - A string value DIE.
   ///
   class DIEString : public DIEValue {
-    const std::string Str;
+    const StringRef Str;
   public:
-    explicit DIEString(const std::string &S) : DIEValue(isString), Str(S) {}
+    explicit DIEString(const StringRef S) : DIEValue(isString), Str(S) {}
 
     /// EmitValue - Emit string value.
     ///
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 4ba156c..f8873a4 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -333,7 +333,7 @@
 /// addString - Add a string attribute data and value.
 ///
 void DwarfDebug::addString(DIE *Die, unsigned Attribute, unsigned Form,
-                           const std::string &String) {
+                           const StringRef String) {
   DIEValue *Value = new DIEString(String);
   DIEValues.push_back(Value);
   Die->addValue(Attribute, Form, Value);
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 01d0e3c..19583b8 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -244,7 +244,7 @@
   /// addString - Add a string attribute data and value.
   ///
   void addString(DIE *Die, unsigned Attribute, unsigned Form,
-                 const std::string &String);
+                 const StringRef Str);
 
   /// addLabel - Add a Dwarf label attribute data and value.
   ///