Index: lib/IR/Attributes.cpp
===================================================================
--- lib/IR/Attributes.cpp
+++ lib/IR/Attributes.cpp
@@ -223,6 +223,21 @@
   return unpackAllocSizeArgs(pImpl->getValueAsInt());
 }
 
+static std::string GetEscapedString(StringRef Name) {
+  std::string EscapedName;
+  for (unsigned i = 0, e = Name.size(); i != e; ++i) {
+    unsigned char C = Name[i];
+    if (isprint(C) && C != '\\' && C != '"')
+      EscapedName += C;
+    else {
+      EscapedName += "\\";
+      EscapedName += hexdigit(C >> 4);
+      EscapedName += hexdigit(C & 0x0F);
+    }
+  }
+  return EscapedName;
+}
+
 std::string Attribute::getAsString(bool InAttrGrp) const {
   if (!pImpl) return "";
 
@@ -384,7 +399,9 @@
     StringRef Val = pImpl->getValueAsString();
     if (Val.empty()) return Result;
 
-    Result += ("=\"" + Val + Twine('"')).str();
+    Result += "=\"";
+    Result += GetEscapedString(Val);
+    Result += "\"";
     return Result;
   }