Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -14941,6 +14941,13 @@
     = FieldDecl::Create(S.Context, Lambda, Loc, Loc, nullptr, FieldType,
                         S.Context.getTrivialTypeSourceInfo(FieldType, Loc),
                         nullptr, false, ICIS_NoInit);
+  // If the variable being captured has an invalid type, mark the lambda class
+  // as invalid as well.
+  if (const CXXRecordDecl *RD = FieldType->getAsCXXRecordDecl()) {
+    if (RD->isInvalidDecl()) {
+      Lambda->setInvalidDecl();
+    }
+  }
   Field->setImplicit(true);
   Field->setAccess(AS_private);
   Lambda->addDecl(Field);
Index: clang/test/SemaCXX/lambda-invalid-capture.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/lambda-invalid-capture.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// Don't crash.
+
+struct g {
+  j; // expected-error {{C++ requires a type specifier for all declarations}}
+};
+
+void h() { 
+  g child;    
+  auto q = [child]{}; 
+  const int n = sizeof(q); 
+}