Index: include/llvm/ADT/Twine.h
===================================================================
--- include/llvm/ADT/Twine.h
+++ include/llvm/ADT/Twine.h
@@ -370,6 +370,13 @@
       assert(isValid() && "Invalid twine!");
     }
 
+    /// Do not construct from StringRef rvalues. Twine stores a *pointer to a
+    /// StringRef*, not a StringRef. Taking the address of a StringRef rvalue
+    /// could easily give us a dangling pointer.
+    /*implicit*/ Twine(StringRef &&) = delete;
+    /*implicit*/ Twine(const char *, StringRef &&) = delete;
+    /*implicit*/ Twine(StringRef &&, const char *) = delete;
+
     /// Create a 'null' string, which is an empty string that always
     /// concatenates to form another empty string.
     static Twine createNull() {
@@ -522,6 +529,8 @@
     return Twine(LHS, RHS);
   }
 
+  inline Twine operator+(const char *, StringRef &&) = delete;
+
   /// Additional overload to guarantee simplified codegen; this is equivalent to
   /// concat().
 
@@ -529,6 +538,8 @@
     return Twine(LHS, RHS);
   }
 
+  inline Twine operator+(StringRef &&, const char *) = delete;
+
   inline raw_ostream &operator<<(raw_ostream &OS, const Twine &RHS) {
     RHS.print(OS);
     return OS;