Index: cfe/trunk/lib/Analysis/CFG.cpp
===================================================================
--- cfe/trunk/lib/Analysis/CFG.cpp
+++ cfe/trunk/lib/Analysis/CFG.cpp
@@ -1390,7 +1390,7 @@
 
   // Check if type is a C++ class with non-trivial destructor.
   if (const CXXRecordDecl *CD = QT->getAsCXXRecordDecl())
-    if (!CD->hasTrivialDestructor()) {
+    if (CD->hasDefinition() && !CD->hasTrivialDestructor()) {
       // Add the variable to scope
       Scope = createOrReuseLocalScope(Scope);
       Scope->addVar(VD);
Index: cfe/trunk/unittests/Analysis/CFGTest.cpp
===================================================================
--- cfe/trunk/unittests/Analysis/CFGTest.cpp
+++ cfe/trunk/unittests/Analysis/CFGTest.cpp
@@ -35,7 +35,9 @@
     if (!Body)
       return;
     TheBuildResult = SawFunctionBody;
-    if (CFG::buildCFG(nullptr, Body, Result.Context, CFG::BuildOptions()))
+    CFG::BuildOptions Options;
+    Options.AddImplicitDtors = true;
+    if (CFG::buildCFG(nullptr, Body, Result.Context, Options))
         TheBuildResult = BuiltCFG;
   }
 };
@@ -75,6 +77,16 @@
   EXPECT_EQ(BuiltCFG, BuildCFG(Code));
 }
 
+// Constructing a CFG on a function template with a variable of incomplete type
+// should not crash.
+TEST(CFG, VariableOfIncompleteType) {
+  const char *Code = "template<class T> void f() {\n"
+                     "  class Undefined;\n"
+                     "  Undefined u;\n"
+                     "}\n";
+  EXPECT_EQ(BuiltCFG, BuildCFG(Code));
+}
+
 } // namespace
 } // namespace analysis
 } // namespace clang