Index: lib/Sema/SemaTemplate.cpp
===================================================================
--- lib/Sema/SemaTemplate.cpp
+++ lib/Sema/SemaTemplate.cpp
@@ -429,7 +429,12 @@
   bool MightBeCxx11UnevalField =
       getLangOpts().CPlusPlus11 && isUnevaluatedContext();
 
-  if (!MightBeCxx11UnevalField && !isAddressOfOperand &&
+  // Check if the nested name specifier is an enum type.
+  bool IsEnum = false;
+  if (NestedNameSpecifier *NNS = SS.getScopeRep())
+    IsEnum = dyn_cast_or_null<EnumType>(NNS->getAsType());
+
+  if (!MightBeCxx11UnevalField && !isAddressOfOperand && !IsEnum &&
       isa<CXXMethodDecl>(DC) && cast<CXXMethodDecl>(DC)->isInstance()) {
     QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType(Context);
 
Index: lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiate.cpp
+++ lib/Sema/SemaTemplateInstantiate.cpp
@@ -1687,7 +1687,7 @@
       // Instantiate default arguments for methods of local classes (DR1484)
       // and non-defining declarations.
       Sema::ContextRAII SavedContext(*this, OwningFunc);
-      LocalInstantiationScope Local(*this);
+      LocalInstantiationScope Local(*this, true);
       ExprResult NewArg = SubstExpr(Arg, TemplateArgs);
       if (NewArg.isUsable()) {
         // It would be nice if we still had this.
Index: lib/Sema/TreeTransform.h
===================================================================
--- lib/Sema/TreeTransform.h
+++ lib/Sema/TreeTransform.h
@@ -10311,6 +10311,18 @@
 
   LSI->CallOperator = NewCallOperator;
 
+  for (unsigned I = 0, NumParams = NewCallOperator->getNumParams();
+       I != NumParams; ++I) {
+    auto *P = NewCallOperator->getParamDecl(I);
+    if (P->hasUninstantiatedDefaultArg()) {
+      EnterExpressionEvaluationContext Eval(
+          getSema(), Sema::PotentiallyEvaluatedIfUsed, P);
+      ExprResult R = getDerived().TransformExpr(
+          E->getCallOperator()->getParamDecl(I)->getDefaultArg());
+      P->setDefaultArg(R.get());
+    }
+  }
+
   getDerived().transformAttrs(E->getCallOperator(), NewCallOperator);
   getDerived().transformedLocalDecl(E->getCallOperator(), NewCallOperator);
 
Index: test/SemaCXX/vartemplate-lambda.cpp
===================================================================
--- test/SemaCXX/vartemplate-lambda.cpp
+++ test/SemaCXX/vartemplate-lambda.cpp
@@ -1,18 +1,36 @@
 // RUN: %clang_cc1 -std=c++14 -fsyntax-only -verify %s
-// expected-no-diagnostics
 
 template <class> auto fn0 = [] {};
 template <typename> void foo0() { fn0<char>(); }
 
 template<typename T> auto fn1 = [](auto a) { return a + T(1); };
+template<typename T> auto v1 = [](int a = T(1)) { return a; }();
+
+struct S {
+  template<class T>
+  static constexpr T t = [](int f = T(7)){return f;}(); // expected-error{{constexpr variable 't<int>' must be initialized by a constant expression}} expected-error{{a lambda expression may not appear inside of a constant expression}} expected-note{{cannot be used in a constant expression}}
+};
 
 template <typename X>
 int foo2() {
   X a = 0x61;
   fn1<char>(a);
+  (void)v1<int>;
+  (void)S::t<int>; // expected-note{{in instantiation of static data member 'S::t<int>' requested here}}
   return 0;
 }
 
+template<class C>
+int foo3() {
+  C::m1(); // expected-error{{type 'long long' cannot be used prior to '::' because it has no members}}
+  return 1;
+}
+
+template<class C>
+auto v2 = [](int a = foo3<C>()){};  // expected-note{{in instantiation of function template specialization 'foo3<long long>' requested here}}
+
 int main() {
+  v2<long long>();  // This line causes foo3<long long> to be instantiated.
+  v2<long long>(2); // This line does not.
   foo2<int>();
 }
Index: test/SemaTemplate/default-expr-arguments-3.cpp
===================================================================
--- /dev/null
+++ test/SemaTemplate/default-expr-arguments-3.cpp
@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 -std=c++14 -emit-llvm -disable-llvm-optzns -verify %s
+// expected-no-diagnostics
+
+namespace PR28795 {
+  template<typename T>
+  void func() {
+    enum class foo { a, b };
+    auto bar = [](foo f = foo::a) { return f; };
+    bar();
+  }
+
+  void foo() {
+    func<int>();
+  }
+}
+
+// Template struct case:
+template <class T> struct class2 {
+  void bar() {
+    enum class foo { a, b };
+    [](foo f = foo::a) { return f; }();
+  }
+};
+
+template struct class2<int>;
+
+template<typename T>
+void f1() {
+  enum class foo { a, b };
+  struct S {
+    int g1(foo n = foo::a);
+  };
+}
+
+template void f1<int>();