Index: utils/TableGen/ClangAttrEmitter.cpp
===================================================================
--- utils/TableGen/ClangAttrEmitter.cpp
+++ utils/TableGen/ClangAttrEmitter.cpp
@@ -718,9 +718,9 @@
   };
 
   // Unique the enums, but maintain the original declaration ordering.
-  std::vector<std::string>
-  uniqueEnumsInOrder(const std::vector<std::string> &enums) {
-    std::vector<std::string> uniques;
+  std::vector<StringRef>
+  uniqueEnumsInOrder(const std::vector<StringRef> &enums) {
+    std::vector<StringRef> uniques;
     SmallDenseSet<StringRef, 8> unique_set;
     for (const auto &i : enums) {
       if (unique_set.insert(i).second)
@@ -731,7 +731,8 @@
 
   class EnumArgument : public Argument {
     std::string type;
-    std::vector<std::string> values, enums, uniques;
+    std::vector<StringRef> values, enums, uniques;
+
   public:
     EnumArgument(const Record &Arg, StringRef Attr)
       : Argument(Arg, Attr), type(Arg.getValueAsString("Type")),
@@ -850,7 +851,7 @@
   
   class VariadicEnumArgument: public VariadicArgument {
     std::string type, QualifiedTypeName;
-    std::vector<std::string> values, enums, uniques;
+    std::vector<StringRef> values, enums, uniques;
 
   protected:
     void writeValueImpl(raw_ostream &OS) const override {
@@ -1591,8 +1592,9 @@
   }
 
   std::string getEnumValueName() const {
-    std::string Result =
-        "SubjectMatchRule_" + MetaSubject->getValueAsString("Name");
+    SmallString<128> Result;
+    Result += "SubjectMatchRule_";
+    Result += MetaSubject->getValueAsString("Name");
     if (isSubRule()) {
       Result += "_";
       if (isNegatedSubRule())
@@ -1601,7 +1603,7 @@
     }
     if (isAbstractRule())
       Result += "_abstract";
-    return Result;
+    return Result.str();
   }
 
   std::string getEnumValue() const { return "attr::" + getEnumValueName(); }
@@ -2603,7 +2605,7 @@
 // append a unique suffix to distinguish this set of target checks from other
 // TargetSpecificAttr records.
 static void GenerateTargetSpecificAttrChecks(const Record *R,
-                                             std::vector<std::string> &Arches,
+                                             std::vector<StringRef> &Arches,
                                              std::string &Test,
                                              std::string *FnName) {
   // It is assumed that there will be an llvm::Triple object
@@ -2613,8 +2615,9 @@
   Test += "(";
 
   for (auto I = Arches.begin(), E = Arches.end(); I != E; ++I) {
-    std::string Part = *I;
-    Test += "T.getArch() == llvm::Triple::" + Part;
+    StringRef Part = *I;
+    Test += "T.getArch() == llvm::Triple::";
+    Test += Part;
     if (I + 1 != E)
       Test += " || ";
     if (FnName)
@@ -2627,11 +2630,12 @@
     // We know that there was at least one arch test, so we need to and in the
     // OS tests.
     Test += " && (";
-    std::vector<std::string> OSes = R->getValueAsListOfStrings("OSes");
+    std::vector<StringRef> OSes = R->getValueAsListOfStrings("OSes");
     for (auto I = OSes.begin(), E = OSes.end(); I != E; ++I) {
-      std::string Part = *I;
+      StringRef Part = *I;
 
-      Test += "T.getOS() == llvm::Triple::" + Part;
+      Test += "T.getOS() == llvm::Triple::";
+      Test += Part;
       if (I + 1 != E)
         Test += " || ";
       if (FnName)
@@ -2643,10 +2647,11 @@
   // If one or more CXX ABIs are specified, check those as well.
   if (!R->isValueUnset("CXXABIs")) {
     Test += " && (";
-    std::vector<std::string> CXXABIs = R->getValueAsListOfStrings("CXXABIs");
+    std::vector<StringRef> CXXABIs = R->getValueAsListOfStrings("CXXABIs");
     for (auto I = CXXABIs.begin(), E = CXXABIs.end(); I != E; ++I) {
-      std::string Part = *I;
-      Test += "Target.getCXXABI().getKind() == TargetCXXABI::" + Part;
+      StringRef Part = *I;
+      Test += "Target.getCXXABI().getKind() == TargetCXXABI::";
+      Test += Part;
       if (I + 1 != E)
         Test += " || ";
       if (FnName)
@@ -2684,7 +2689,7 @@
     std::string Test;
     if (Attr->isSubClassOf("TargetSpecificAttr")) {
       const Record *R = Attr->getValueAsDef("Target");
-      std::vector<std::string> Arches = R->getValueAsListOfStrings("Arches");
+      std::vector<StringRef> Arches = R->getValueAsListOfStrings("Arches");
       GenerateTargetSpecificAttrChecks(R, Arches, Test, nullptr);
 
       // If this is the C++11 variety, also add in the LangOpts test.
@@ -3323,7 +3328,7 @@
 
   // Get the list of architectures to be tested for.
   const Record *R = Attr.getValueAsDef("Target");
-  std::vector<std::string> Arches = R->getValueAsListOfStrings("Arches");
+  std::vector<StringRef> Arches = R->getValueAsListOfStrings("Arches");
   if (Arches.empty()) {
     PrintError(Attr.getLoc(), "Empty list of target architectures for a "
                               "target-specific attr");
@@ -3340,9 +3345,10 @@
     std::string APK = Attr.getValueAsString("ParseKind");
     for (const auto &I : Dupes) {
       if (I.first == APK) {
-        std::vector<std::string> DA = I.second->getValueAsDef("Target")
-                                          ->getValueAsListOfStrings("Arches");
-        std::move(DA.begin(), DA.end(), std::back_inserter(Arches));
+        std::vector<StringRef> DA =
+            I.second->getValueAsDef("Target")->getValueAsListOfStrings(
+                "Arches");
+        Arches.insert(Arches.end(), DA.begin(), DA.end());
       }
     }
   }
Index: utils/TableGen/ClangDiagnosticsEmitter.cpp
===================================================================
--- utils/TableGen/ClangDiagnosticsEmitter.cpp
+++ utils/TableGen/ClangDiagnosticsEmitter.cpp
@@ -1278,7 +1278,7 @@
                      GroupInfo.SubGroups.size() == 1;
 
     writeHeader((IsRemarkGroup ? "-R" : "-W") +
-                    G->getValueAsString("GroupName"),
+                    G->getValueAsString("GroupName").str(),
                 OS);
 
     if (!IsSynonym) {
Index: utils/TableGen/ClangOptionDocEmitter.cpp
===================================================================
--- utils/TableGen/ClangOptionDocEmitter.cpp
+++ utils/TableGen/ClangOptionDocEmitter.cpp
@@ -83,7 +83,7 @@
     }
 
     // Pretend no-X and Xno-Y options are aliases of X and XY.
-    auto Name = R->getValueAsString("Name");
+    std::string Name = R->getValueAsString("Name");
     if (Name.size() >= 4) {
       if (Name.substr(0, 3) == "no-" && OptionsByName[Name.substr(3)]) {
         Aliases[OptionsByName[Name.substr(3)]].push_back(R);
@@ -267,8 +267,9 @@
   if (!AliasArgs.empty()) {
     Record *Alias = Option->getValueAsDef("Alias");
     OS << " (equivalent to ";
-    emitOptionWithArgs(Alias->getValueAsListOfStrings("Prefixes").front(),
-                       Alias, Option->getValueAsListOfStrings("AliasArgs"), OS);
+    emitOptionWithArgs(
+        Alias->getValueAsListOfStrings("Prefixes").front(), Alias,
+        std::vector<std::string>(AliasArgs.begin(), AliasArgs.end()), OS);
     OS << ")";
   }
 }
@@ -310,7 +311,7 @@
   forEachOptionName(Option, DocInfo, [&](const Record *Option) {
     for (auto &Prefix : Option->getValueAsListOfStrings("Prefixes"))
       SphinxOptionIDs.push_back(
-          getSphinxOptionID(Prefix + Option->getValueAsString("Name")));
+          getSphinxOptionID((Prefix + Option->getValueAsString("Name")).str()));
   });
   assert(!SphinxOptionIDs.empty() && "no flags for option");
   static std::map<std::string, int> NextSuffix;
Index: utils/TableGen/ClangSACheckersEmitter.cpp
===================================================================
--- utils/TableGen/ClangSACheckersEmitter.cpp
+++ utils/TableGen/ClangSACheckersEmitter.cpp
@@ -51,7 +51,8 @@
 static std::string getPackageFullName(const Record *R) {
   std::string name = getParentPackageFullName(R);
   if (!name.empty()) name += ".";
-  return name + R->getValueAsString("PackageName");
+  name += R->getValueAsString("PackageName");
+  return name;
 }
 
 static std::string getCheckerFullName(const Record *R) {