diff --git a/clang/lib/AST/ComputeDependence.cpp b/clang/lib/AST/ComputeDependence.cpp
--- a/clang/lib/AST/ComputeDependence.cpp
+++ b/clang/lib/AST/ComputeDependence.cpp
@@ -466,10 +466,12 @@
              : Var->getType()->isIntegralOrEnumerationType()) &&
         (Var->getType().isConstQualified() ||
          Var->getType()->isReferenceType())) {
-      if (const Expr *Init = Var->getAnyInitializer())
-        if (Init->isValueDependent()) {
+      if (const Expr *Init = Var->getAnyInitializer()) {
+        if (Init->isValueDependent())
           Deps |= ExprDependence::ValueInstantiation;
-        }
+        if (Init->containsErrors())
+          Deps |= ExprDependence::Error;
+      }
     }
 
     // (VD) - FIXME: Missing from the standard:
diff --git a/clang/test/Sema/invalid-member.cpp b/clang/test/Sema/invalid-member.cpp
--- a/clang/test/Sema/invalid-member.cpp
+++ b/clang/test/Sema/invalid-member.cpp
@@ -19,3 +19,10 @@
 };
 // Should be able to evaluate sizeof without crashing.
 static_assert(sizeof(Z) == 1, "No valid members");
+
+constexpr int N = undef; // expected-error {{use of undeclared identifier}}
+
+class T {
+  decltype(N) member;
+};
+static_assert(sizeof(T) == 1, "No valid members");
diff --git a/clang/test/SemaCXX/invalid-template-base-specifier.cpp b/clang/test/SemaCXX/invalid-template-base-specifier.cpp
--- a/clang/test/SemaCXX/invalid-template-base-specifier.cpp
+++ b/clang/test/SemaCXX/invalid-template-base-specifier.cpp
@@ -26,3 +26,10 @@
 };
 
 void test3() { Crash3<int>(); } // expected-note {{in instantiation of template class}}
+
+constexpr int N = undef; // expected-error {{use of undeclared identifier}}
+
+class Crash4 : decltype(N) {
+};
+
+static_assert(sizeof(Crash4) == 1, "");