diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index ca4de55fb51c57315eaacccc00d5b7fcccd4a636..9122030e16d7634dd2b623ed7c170f12ae0dc8bf 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -11274,9 +11274,8 @@ Sema::CheckForFunctionRedefinition(FunctionDecl *FD,
     SkipBody->ShouldSkip = true;
     if (auto *TD = Definition->getDescribedFunctionTemplate())
       makeMergedDefinitionVisible(TD, FD->getLocation());
-    else
-      makeMergedDefinitionVisible(const_cast<FunctionDecl*>(Definition),
-                                  FD->getLocation());
+    makeMergedDefinitionVisible(const_cast<FunctionDecl*>(Definition),
+                                FD->getLocation());
     return;
   }
 
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index ede1c5bcc64166c6233396cdf7a88a3511b2890c..6241f524af283b4a85df8490c0645fa0a470f016 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -487,8 +487,6 @@ bool Sema::DiagnoseUninstantiableTemplate(SourceLocation PointOfInstantiation,
   QualType InstantiationTy;
   if (TagDecl *TD = dyn_cast<TagDecl>(Instantiation))
     InstantiationTy = Context.getTypeDeclType(TD);
-  else
-    InstantiationTy = cast<FunctionDecl>(Instantiation)->getType();
   if (!Complain || (PatternDef && PatternDef->isInvalidDecl())) {
     // Say nothing
   } else if (PatternDef) {
@@ -500,15 +498,30 @@ bool Sema::DiagnoseUninstantiableTemplate(SourceLocation PointOfInstantiation,
     // we're lexically inside it.
     Instantiation->setInvalidDecl();
   } else if (InstantiatedFromMember) {
-    Diag(PointOfInstantiation,
-         diag::err_implicit_instantiate_member_undefined)
-      << InstantiationTy;
-    Diag(Pattern->getLocation(), diag::note_member_declared_at);
+    if (isa<FunctionDecl>(Instantiation)) {
+      Diag(PointOfInstantiation,
+           diag::err_explicit_instantiation_undefined_member)
+        << 1 << Instantiation->getDeclName() << Instantiation->getDeclContext();
+    } else {
+      Diag(PointOfInstantiation,
+           diag::err_implicit_instantiate_member_undefined)
+        << InstantiationTy;
+    }
+    Diag(Pattern->getLocation(), isa<FunctionDecl>(Instantiation)
+                                     ? diag::note_explicit_instantiation_here
+                                     : diag::note_member_declared_at);
   } else {
-    Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
-      << (TSK != TSK_ImplicitInstantiation)
-      << InstantiationTy;
-    Diag(Pattern->getLocation(), diag::note_template_decl_here);
+    if (isa<FunctionDecl>(Instantiation))
+      Diag(PointOfInstantiation,
+           diag::err_explicit_instantiation_undefined_func_template)
+        << Pattern;
+    else
+      Diag(PointOfInstantiation, diag::err_template_instantiate_undefined)
+        << (TSK != TSK_ImplicitInstantiation)
+        << InstantiationTy;
+    Diag(Pattern->getLocation(), isa<FunctionDecl>(Instantiation)
+                                     ? diag::note_explicit_instantiation_here
+                                     : diag::note_template_decl_here);
   }
 
   // In general, Instantiation isn't marked invalid to get more than one
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 3f4a0f6f39a673765d628484e6ed79c7612f7caf..75d7f70a6368e2f3cf0f6ae005a722385377b4c2 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3554,23 +3554,38 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
   const FunctionDecl *PatternDecl = Function->getTemplateInstantiationPattern();
   assert(PatternDecl && "instantiating a non-template");
 
-  Stmt *Pattern = PatternDecl->getBody(PatternDecl);
-  assert(PatternDecl && "template definition is not a template");
-  if (!Pattern) {
-    // Try to find a defaulted definition
-    PatternDecl->isDefined(PatternDecl);
-  }
-  assert(PatternDecl && "template definition is not a template");
+  const FunctionDecl *PatternDef = PatternDecl->getDefinition();
+  Stmt *Pattern = PatternDef->getBody(PatternDef);
+  if (PatternDef)
+    PatternDecl = PatternDef;
 
   // FIXME: We need to track the instantiation stack in order to know which
   // definitions should be visible within this instantiation.
   if (DiagnoseUninstantiableTemplate(PointOfInstantiation, Function,
                                 Function->getInstantiatedFromMemberFunction(),
-                                     PatternDecl, PatternDecl, TSK,
-                                     /*Complain*/DefinitionRequired))
-     return;
-
+                                     PatternDecl, PatternDef, TSK,
+                                     /*Complain*/DefinitionRequired)) {
+    if (DefinitionRequired)
+      Function->setInvalidDecl();
+    else if (TSK == TSK_ExplicitInstantiationDefinition) {
+      // Try again at the end of the translation unit (at which point a
+      // definition will be required).
+      assert(!Recursive);
+      PendingInstantiations.push_back(
+        std::make_pair(Function, PointOfInstantiation));
+    } else if (TSK == TSK_ImplicitInstantiation) {
+      if (AtEndOfTU && !getDiagnostics().hasErrorOccurred()) {
+        Diag(PointOfInstantiation, diag::warn_func_template_missing)
+          << Function;
+        Diag(PatternDecl->getLocation(), diag::note_forward_template_decl);
+        if (getLangOpts().CPlusPlus11)
+          Diag(PointOfInstantiation, diag::note_inst_declaration_hint)
+            << Function;
+      }
+    }
 
+    return;
+  }
 
   // Postpone late parsed template instantiations.
   if (PatternDecl->isLateTemplateParsed() &&
@@ -3604,40 +3619,9 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
     Pattern = PatternDecl->getBody(PatternDecl);
   }
 
-  // FIXME: Check if we could sink these diagnostics in
-  // DiagnoseUninstantiableTemplate.
-  if (!Pattern && !PatternDecl->isDefaulted()) {
-    if (DefinitionRequired) {
-      if (Function->getPrimaryTemplate())
-        Diag(PointOfInstantiation,
-             diag::err_explicit_instantiation_undefined_func_template)
-          << Function->getPrimaryTemplate();
-      else
-        Diag(PointOfInstantiation,
-             diag::err_explicit_instantiation_undefined_member)
-          << 1 << Function->getDeclName() << Function->getDeclContext();
-
-      if (PatternDecl)
-        Diag(PatternDecl->getLocation(),
-             diag::note_explicit_instantiation_here);
-      Function->setInvalidDecl();
-    } else if (TSK == TSK_ExplicitInstantiationDefinition) {
-      assert(!Recursive);
-      PendingInstantiations.push_back(
-        std::make_pair(Function, PointOfInstantiation));
-    } else if (TSK == TSK_ImplicitInstantiation) {
-      if (AtEndOfTU && !getDiagnostics().hasErrorOccurred()) {
-        Diag(PointOfInstantiation, diag::warn_func_template_missing)
-          << Function;
-        Diag(PatternDecl->getLocation(), diag::note_forward_template_decl);
-        if (getLangOpts().CPlusPlus11)
-          Diag(PointOfInstantiation, diag::note_inst_declaration_hint)
-            << Function;
-      }
-    }
-
-    return;
-  }
+  // Note, we should never try to instantiate a deleted function template.
+  assert((Pattern || PatternDecl->isDefaulted()) &&
+         "unexpected kind of function template definition");
 
   // C++1y [temp.explicit]p10:
   //   Except for inline functions, declarations with types deduced from their
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 091a4e34e19543c490e77bc4c40d9cd73fc5bcce..8a49f6120cf8e82254c8184004884044366614ca 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -6890,6 +6890,10 @@ bool Sema::hasVisibleDefinition(NamedDecl *D, NamedDecl **Suggested,
       return false;
     }
     D = ED->getDefinition();
+  } else if (auto *FD = dyn_cast<FunctionDecl>(D)) {
+    if (auto *Pattern = FD->getTemplateInstantiationPattern())
+      FD = Pattern;
+    D = FD->getDefinition();
   }
   assert(D && "missing definition for pattern of instantiated definition");
 
@@ -6897,7 +6901,7 @@ bool Sema::hasVisibleDefinition(NamedDecl *D, NamedDecl **Suggested,
   if (isVisible(D))
     return true;
 
-  // The external source may have additional definitions of this type that are
+  // The external source may have additional definitions of this entity that are
   // visible, so complete the redeclaration chain now and ask again.
   if (auto *Source = Context.getExternalSource()) {
     Source->CompleteRedeclChain(D);
diff --git a/test/Modules/Inputs/merge-template-pattern-visibility/a.h b/test/Modules/Inputs/merge-template-pattern-visibility/a.h
index 7f9b6497e7250cdb8f54984435384aac91b9b57b..e6592027611c2f91d7d09dfc6ca0d7dd1a3724d5 100644
--- a/test/Modules/Inputs/merge-template-pattern-visibility/a.h
+++ b/test/Modules/Inputs/merge-template-pattern-visibility/a.h
@@ -3,3 +3,4 @@ template<typename T> struct B;
 
 template<typename, typename> struct A {};
 template<typename T> struct B : A<T> {};
+template<typename T> inline auto C(T) {}
diff --git a/test/Modules/Inputs/merge-template-pattern-visibility/b.h b/test/Modules/Inputs/merge-template-pattern-visibility/b.h
index 5ed18e7e7c5d9745925b343c305e43ad2cb07c68..6db3c2c6c9f873a7007a95199785f05c914f6c16 100644
--- a/test/Modules/Inputs/merge-template-pattern-visibility/b.h
+++ b/test/Modules/Inputs/merge-template-pattern-visibility/b.h
@@ -3,7 +3,9 @@ template<typename T> struct B;
 
 template<typename, typename> struct A {};
 template<typename T> struct B : A<T> {};
+template<typename T> inline auto C(T) {}
 
 inline void f() {
   B<int> bi;
+  C(0);
 }
diff --git a/test/Modules/merge-template-pattern-visibility.cpp b/test/Modules/merge-template-pattern-visibility.cpp
index db759b5a46a12e179d048f2ba9062206cf85bf0e..b97f9f113e3b96f40213415d6603cb66ed57bde3 100644
--- a/test/Modules/merge-template-pattern-visibility.cpp
+++ b/test/Modules/merge-template-pattern-visibility.cpp
@@ -1,4 +1,4 @@
 // RUN: rm -rf %t
-// RUN: %clang_cc1 -fmodules -fmodules-cache-path=%t -fno-modules-error-recovery \
+// RUN: %clang_cc1 -fmodules -fno-modules-error-recovery -std=c++14 \
 // RUN:            -fmodule-name=X -emit-module %S/Inputs/merge-template-pattern-visibility/module.modulemap -x c++ \
-// RUN:            -fmodules-local-submodule-visibility
+// RUN:            -fmodules-local-submodule-visibility -o %t/X.pcm