Index: include/clang/Sema/TemplateDeduction.h
===================================================================
--- include/clang/Sema/TemplateDeduction.h
+++ include/clang/Sema/TemplateDeduction.h
@@ -68,8 +68,10 @@
   /// \brief Take ownership of the SFINAE diagnostic.
   void takeSFINAEDiagnostic(PartialDiagnosticAt &PD) {
     assert(HasSFINAEDiagnostic);
-    PD.first = SuppressedDiagnostics.front().first;
-    PD.second.swap(SuppressedDiagnostics.front().second);
+    unsigned NumberOfDiagnostics = SuppressedDiagnostics.size();
+    PartialDiagnosticAt &PDiag = SuppressedDiagnostics[((NumberOfDiagnostics == 2) ? 1 : 0)];
+    PD.first = PDiag.first;
+    PD.second.swap(PDiag.second);
     SuppressedDiagnostics.clear();
     HasSFINAEDiagnostic = false;
   }
@@ -98,8 +100,6 @@
   /// \brief Add a new diagnostic to the set of diagnostics
   void addSuppressedDiagnostic(SourceLocation Loc,
                                PartialDiagnostic PD) {
-    if (HasSFINAEDiagnostic)
-      return;
     SuppressedDiagnostics.emplace_back(Loc, std::move(PD));
   }
 
Index: lib/Sema/SemaOverload.cpp
===================================================================
--- lib/Sema/SemaOverload.cpp
+++ lib/Sema/SemaOverload.cpp
@@ -9105,6 +9105,16 @@
       return;
     }
 
+    // If the diagnsotics is already for overload candidate substitution
+    // failure, then just emit the diagnostics as is.
+    if (PDiag && (PDiag->second.getDiagID() ==
+                      diag::note_ovl_candidate_substitution_failure ||
+                  PDiag->second.getDiagID() ==
+                      diag::note_ovl_candidate_disabled_by_enable_if)) {
+      S.Diag(PDiag->first, PDiag->second);
+      return;
+    }
+
     // Format the SFINAE diagnostic into the argument string.
     // FIXME: Add a general mechanism to include a PartialDiagnostic *'s
     //        formatted message in another diagnostic.
@@ -9116,7 +9126,7 @@
       PDiag->second.EmitToString(S.getDiagnostics(), SFINAEArgString);
     }
 
-    S.Diag(Templated->getLocation(),
+    S.Diag(PDiag->first,
            diag::note_ovl_candidate_substitution_failure)
         << TemplateArgString << SFINAEArgString << R;
     MaybeEmitInheritedConstructorNote(S, Templated);