Index: clang/lib/CodeGen/CodeGenAction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenAction.cpp
+++ clang/lib/CodeGen/CodeGenAction.cpp
@@ -86,7 +86,7 @@
   };
 
   static void reportOptRecordError(Error E, DiagnosticsEngine &Diags,
-                                   const CodeGenOptions CodeGenOpts) {
+                                   const CodeGenOptions &CodeGenOpts) {
     handleAllErrors(
         std::move(E),
       [&](const LLVMRemarkSetupFileError &E) {
Index: clang/lib/Sema/SemaCodeComplete.cpp
===================================================================
--- clang/lib/Sema/SemaCodeComplete.cpp
+++ clang/lib/Sema/SemaCodeComplete.cpp
@@ -4148,7 +4148,7 @@
 
 static void HandleCodeCompleteResults(Sema *S,
                                       CodeCompleteConsumer *CodeCompleter,
-                                      CodeCompletionContext Context,
+                                      const CodeCompletionContext &Context,
                                       CodeCompletionResult *Results,
                                       unsigned NumResults) {
   if (CodeCompleter)
Index: clang/lib/Sema/SemaConcept.cpp
===================================================================
--- clang/lib/Sema/SemaConcept.cpp
+++ clang/lib/Sema/SemaConcept.cpp
@@ -160,7 +160,7 @@
   Sema &SemaRef;
   bool Inserted = false;
   SatisfactionStackRAII(Sema &SemaRef, const NamedDecl *ND,
-                        llvm::FoldingSetNodeID FSNID)
+                        const llvm::FoldingSetNodeID &FSNID)
       : SemaRef(SemaRef) {
       if (ND) {
       SemaRef.PushSatisfactionStackEntry(ND, FSNID);
@@ -1370,7 +1370,7 @@
 }
 
 template<typename AtomicSubsumptionEvaluator>
-static bool subsumes(NormalForm PDNF, NormalForm QCNF,
+static bool subsumes(const NormalForm &PDNF, const NormalForm &QCNF,
                      AtomicSubsumptionEvaluator E) {
   // C++ [temp.constr.order] p2
   //   Then, P subsumes Q if and only if, for every disjunctive clause Pi in the