diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -2426,7 +2426,10 @@
                          TypeSourceInfo *TInfo,
                          SourceLocation EllipsisLoc) {
   QualType BaseType = TInfo->getType();
-
+  if (BaseType->containsErrors()) {
+    // Already emitted a diagnostic when parsing the error type.
+    return nullptr;
+  }
   // C++ [class.union]p1:
   //   A union shall not have base classes.
   if (Class->isUnion()) {
diff --git a/clang/test/SemaCXX/invalid-template-base-specifier.cpp b/clang/test/SemaCXX/invalid-template-base-specifier.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaCXX/invalid-template-base-specifier.cpp
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -frecovery-ast -verify %s
+
+bool Foo(int *); // expected-note {{candidate function not viable}}
+
+template <typename T>
+struct Crash : decltype(Foo(T())) { // expected-error {{no matching function for call to 'Foo'}}
+  Crash(){};
+};
+
+void test() { Crash<int>(); } // expected-note {{in instantiation of template class}}