Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -5151,7 +5151,8 @@
                                bool UseGlobal, QualType AllocType, bool IsArray,
                                bool &PassAlignment, MultiExprArg PlaceArgs,
                                FunctionDecl *&OperatorNew,
-                               FunctionDecl *&OperatorDelete);
+                               FunctionDecl *&OperatorDelete,
+                               bool Diagnose = true);
   void DeclareGlobalNewDelete();
   void DeclareGlobalAllocationFunction(DeclarationName Name, QualType Return,
                                        ArrayRef<QualType> Params);
Index: lib/Sema/SemaExprCXX.cpp
===================================================================
--- lib/Sema/SemaExprCXX.cpp
+++ lib/Sema/SemaExprCXX.cpp
@@ -2151,12 +2151,10 @@
   return false;
 }
 
-static bool
-resolveAllocationOverload(Sema &S, LookupResult &R, SourceRange Range,
-                          SmallVectorImpl<Expr *> &Args, bool &PassAlignment,
-                          FunctionDecl *&Operator,
-                          OverloadCandidateSet *AlignedCandidates = nullptr,
-                          Expr *AlignArg = nullptr) {
+static bool resolveAllocationOverload(
+    Sema &S, LookupResult &R, SourceRange Range, SmallVectorImpl<Expr *> &Args,
+    bool &PassAlignment, FunctionDecl *&Operator,
+    OverloadCandidateSet *AlignedCandidates, Expr *AlignArg, bool Diagnose) {
   OverloadCandidateSet Candidates(R.getNameLoc(),
                                   OverloadCandidateSet::CSK_Normal);
   for (LookupResult::iterator Alloc = R.begin(), AllocEnd = R.end();
@@ -2202,7 +2200,8 @@
       AlignArg = Args[1];
       Args.erase(Args.begin() + 1);
       return resolveAllocationOverload(S, R, Range, Args, PassAlignment,
-                                       Operator, &Candidates, AlignArg);
+                                       Operator, &Candidates, AlignArg,
+                                       Diagnose);
     }
 
     // MSVC will fall back on trying to find a matching global operator new
@@ -2218,48 +2217,53 @@
       S.LookupQualifiedName(R, S.Context.getTranslationUnitDecl());
       // FIXME: This will give bad diagnostics pointing at the wrong functions.
       return resolveAllocationOverload(S, R, Range, Args, PassAlignment,
-                                       Operator, nullptr);
+                                       Operator, /*Candidates=*/nullptr,
+                                       /*AlignArg=*/nullptr, Diagnose);
     }
 
-    S.Diag(R.getNameLoc(), diag::err_ovl_no_viable_function_in_call)
-      << R.getLookupName() << Range;
+    if (Diagnose) {
+      S.Diag(R.getNameLoc(), diag::err_ovl_no_viable_function_in_call)
+          << R.getLookupName() << Range;
 
-    // If we have aligned candidates, only note the align_val_t candidates
-    // from AlignedCandidates and the non-align_val_t candidates from
-    // Candidates.
-    if (AlignedCandidates) {
-      auto IsAligned = [](OverloadCandidate &C) {
-        return C.Function->getNumParams() > 1 &&
-               C.Function->getParamDecl(1)->getType()->isAlignValT();
-      };
-      auto IsUnaligned = [&](OverloadCandidate &C) { return !IsAligned(C); };
-
-      // This was an overaligned allocation, so list the aligned candidates
-      // first.
-      Args.insert(Args.begin() + 1, AlignArg);
-      AlignedCandidates->NoteCandidates(S, OCD_AllCandidates, Args, "",
-                                        R.getNameLoc(), IsAligned);
-      Args.erase(Args.begin() + 1);
-      Candidates.NoteCandidates(S, OCD_AllCandidates, Args, "", R.getNameLoc(),
-                                IsUnaligned);
-    } else {
-      Candidates.NoteCandidates(S, OCD_AllCandidates, Args);
+      // If we have aligned candidates, only note the align_val_t candidates
+      // from AlignedCandidates and the non-align_val_t candidates from
+      // Candidates.
+      if (AlignedCandidates) {
+        auto IsAligned = [](OverloadCandidate &C) {
+          return C.Function->getNumParams() > 1 &&
+                 C.Function->getParamDecl(1)->getType()->isAlignValT();
+        };
+        auto IsUnaligned = [&](OverloadCandidate &C) { return !IsAligned(C); };
+
+        // This was an overaligned allocation, so list the aligned candidates
+        // first.
+        Args.insert(Args.begin() + 1, AlignArg);
+        AlignedCandidates->NoteCandidates(S, OCD_AllCandidates, Args, "",
+                                          R.getNameLoc(), IsAligned);
+        Args.erase(Args.begin() + 1);
+        Candidates.NoteCandidates(S, OCD_AllCandidates, Args, "", R.getNameLoc(),
+                                  IsUnaligned);
+      } else {
+        Candidates.NoteCandidates(S, OCD_AllCandidates, Args);
+      }
     }
     return true;
 
   case OR_Ambiguous:
-    S.Diag(R.getNameLoc(), diag::err_ovl_ambiguous_call)
-      << R.getLookupName() << Range;
-    Candidates.NoteCandidates(S, OCD_ViableCandidates, Args);
+    if (Diagnose) {
+      S.Diag(R.getNameLoc(), diag::err_ovl_ambiguous_call)
+          << R.getLookupName() << Range;
+      Candidates.NoteCandidates(S, OCD_ViableCandidates, Args);
+    }
     return true;
 
   case OR_Deleted: {
-    S.Diag(R.getNameLoc(), diag::err_ovl_deleted_call)
-      << Best->Function->isDeleted()
-      << R.getLookupName()
-      << S.getDeletedOrUnavailableSuffix(Best->Function)
-      << Range;
-    Candidates.NoteCandidates(S, OCD_AllCandidates, Args);
+    if (Diagnose) {
+      S.Diag(R.getNameLoc(), diag::err_ovl_deleted_call)
+          << Best->Function->isDeleted() << R.getLookupName()
+          << S.getDeletedOrUnavailableSuffix(Best->Function) << Range;
+      Candidates.NoteCandidates(S, OCD_AllCandidates, Args);
+    }
     return true;
   }
   }
@@ -2274,7 +2278,8 @@
                                    bool IsArray, bool &PassAlignment,
                                    MultiExprArg PlaceArgs,
                                    FunctionDecl *&OperatorNew,
-                                   FunctionDecl *&OperatorDelete) {
+                                   FunctionDecl *&OperatorDelete,
+                                   bool Diagnose) {
   // --- Choosing an allocation function ---
   // C++ 5.3.4p8 - 14 & 18
   // 1) If UseGlobal is true, only look in the global scope. Else, also look
@@ -2349,7 +2354,8 @@
     R.suppressDiagnostics();
 
     if (resolveAllocationOverload(*this, R, Range, AllocArgs, PassAlignment,
-                                  OperatorNew))
+                                  OperatorNew, /*Candidates=*/nullptr,
+                                  /*AlignArg=*/nullptr, Diagnose))
       return true;
   }