Index: lib/Sema/SemaTemplateDeduction.cpp
===================================================================
--- lib/Sema/SemaTemplateDeduction.cpp
+++ lib/Sema/SemaTemplateDeduction.cpp
@@ -1284,10 +1284,6 @@
     return Sema::TDK_Success;
   }
 
-  // Set up the template argument deduction information for a failure.
-  Info.FirstArg = TemplateArgument(ParamIn);
-  Info.SecondArg = TemplateArgument(ArgIn);
-
   // If the parameter is an already-substituted template parameter
   // pack, do nothing: we don't know which of its arguments to look
   // at, so we have to wait until all of the parameter packs in this
@@ -1295,6 +1291,13 @@
   if (isa<SubstTemplateTypeParmPackType>(Param))
     return Sema::TDK_Success;
 
+  // Set up the template argument deduction information for a failure.
+  // Save the original values in case deduction succeeds.
+  TemplateArgument OriginalFirstArg = Info.FirstArg;
+  TemplateArgument OriginalSecondArg = Info.SecondArg;
+  Info.FirstArg = TemplateArgument(ParamIn);
+  Info.SecondArg = TemplateArgument(ArgIn);
+
   // Check the cv-qualifiers on the parameter and argument types.
   CanQualType CanParam = S.Context.getCanonicalType(Param);
   CanQualType CanArg = S.Context.getCanonicalType(Arg);
@@ -1318,7 +1321,7 @@
           return Sema::TDK_NonDeducedMismatch;
         }
       }
-      return Sema::TDK_Success;
+      goto Success;
     }
   } else if (!Param->isDependentType()) {
     CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
@@ -1328,7 +1331,7 @@
             ? S.isSameOrCompatibleFunctionType(ParamUnqualType, ArgUnqualType)
             : ParamUnqualType == ArgUnqualType;
     if (Success)
-      return Sema::TDK_Success;
+      goto Success;
   }
 
   switch (Param->getTypeClass()) {
@@ -1354,14 +1357,17 @@
     case Type::ObjCInterface:
     case Type::ObjCObjectPointer: {
       if (TDF & TDF_SkipNonDependent)
-        return Sema::TDK_Success;
+        goto Success;
 
       if (TDF & TDF_IgnoreQualifiers) {
         Param = Param.getUnqualifiedType();
         Arg = Arg.getUnqualifiedType();
       }
 
-      return Param == Arg? Sema::TDK_Success : Sema::TDK_NonDeducedMismatch;
+      if (Param == Arg)
+        goto Success;
+
+      return Sema::TDK_NonDeducedMismatch;
     }
 
     //     _Complex T   [placeholder extension]
@@ -1483,7 +1489,7 @@
       NonTypeTemplateParmDecl *NTTP
         = getDeducedParameterFromExpr(Info, DependentArrayParm->getSizeExpr());
       if (!NTTP)
-        return Sema::TDK_Success;
+        goto Success;
 
       // We can perform template argument deduction for the given non-type
       // template parameter.
@@ -1543,7 +1549,7 @@
         return Result;
 
       if (TDF & TDF_AllowCompatibleFunctionType)
-        return Sema::TDK_Success;
+        goto Success;
 
       // FIXME: Per core-2016/10/1019 (no corresponding core issue yet), permit
       // deducing through the noexcept-specifier if it's part of the canonical
@@ -1578,7 +1584,7 @@
       }
       // FIXME: Detect non-deduced exception specification mismatches?
 
-      return Sema::TDK_Success;
+      goto Success;
     }
 
     case Type::InjectedClassName: {
@@ -1614,7 +1620,7 @@
           S, TemplateParams, SpecParam, Arg, Info, Deduced);
 
       if (Result == Sema::TDK_Success)
-        return Result;
+        goto Success;
 
       // We cannot inspect base classes as part of deduction when the type
       // is incomplete, so either instantiate any templates necessary to
@@ -1691,7 +1697,7 @@
 
       if (Successful) {
         std::swap(SuccessfulDeduced, Deduced);
-        return Sema::TDK_Success;
+        goto Success;
       }
 
       return Result;
@@ -1807,7 +1813,7 @@
         NonTypeTemplateParmDecl *NTTP
           = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
         if (!NTTP)
-          return Sema::TDK_Success;
+          goto Success;
 
         llvm::APSInt ArgSize(S.Context.getTypeSize(S.Context.IntTy), false);
         ArgSize = VectorArg->getNumElements();
@@ -1833,7 +1839,7 @@
         NonTypeTemplateParmDecl *NTTP
           = getDeducedParameterFromExpr(Info, VectorParam->getSizeExpr());
         if (!NTTP)
-          return Sema::TDK_Success;
+          goto Success;
 
         return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
                                              VectorArg->getSizeExpr(),
@@ -1863,7 +1869,7 @@
         NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
             Info, AddressSpaceParam->getAddrSpaceExpr());
         if (!NTTP)
-          return Sema::TDK_Success;
+          goto Success;
 
         return DeduceNonTypeTemplateArgument(
             S, TemplateParams, NTTP, AddressSpaceArg->getAddrSpaceExpr(), Info,
@@ -1886,7 +1892,7 @@
         NonTypeTemplateParmDecl *NTTP = getDeducedParameterFromExpr(
             Info, AddressSpaceParam->getAddrSpaceExpr());
         if (!NTTP)
-          return Sema::TDK_Success;
+          goto Success;
 
         return DeduceNonTypeTemplateArgument(S, TemplateParams, NTTP,
                                              ArgAddressSpace, S.Context.IntTy,
@@ -1908,10 +1914,15 @@
     case Type::PackExpansion:
     case Type::Pipe:
       // No template argument deduction for these types
-      return Sema::TDK_Success;
+      goto Success;
   }
 
   llvm_unreachable("Invalid Type Class!");
+
+Success:
+  Info.FirstArg = OriginalFirstArg;
+  Info.SecondArg = OriginalSecondArg;
+  return Sema::TDK_Success;
 }
 
 static Sema::TemplateDeductionResult
Index: test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/basic.cpp
===================================================================
--- test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/basic.cpp
+++ test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/basic.cpp
@@ -45,3 +45,11 @@
     func(foo<int>()); // expected-error {{no matching function}}
   }
 }
+
+namespace test4 {
+  // expected-note@+1 {{candidate template ignored: could not match 'int [N]' against 'int []'}}
+  template<int N> void f1(int (&arr)[N]);
+  template<int N> void f2(int (&arr)[]) {
+    f1(arr); // expected-error {{no matching function}}
+  }
+}