diff --git a/lib/Demangling/OldRemangler.cpp b/lib/Demangling/OldRemangler.cpp
index dfc27c9b15dcb..d4b1932a47a35 100644
--- a/lib/Demangling/OldRemangler.cpp
+++ b/lib/Demangling/OldRemangler.cpp
@@ -3051,5 +3051,7 @@ ManglingError Remangler::mangleHasSymbolQuery(Node *node, unsigned depth) {
 ManglingError
 Remangler::mangleDependentGenericInverseConformanceRequirement(Node *node,
                                                                unsigned depth) {
-  return MANGLING_ERROR(ManglingError::UnsupportedNodeKind, node);
+  DEMANGLER_ASSERT(node->getNumChildren() == 2, node);
+  RETURN_IF_ERROR(mangleConstrainedType(node->getChild(0), depth + 1));
+  return mangle(node->getChild(1), depth + 1);
 }
diff --git a/test/IRGen/non-copyable-class-mangling.swift b/test/IRGen/non-copyable-class-mangling.swift
new file mode 100644
index 0000000000000..5319af6cd5fc6
--- /dev/null
+++ b/test/IRGen/non-copyable-class-mangling.swift
@@ -0,0 +1,11 @@
+// RUN: %target-swift-frontend %s -emit-ir -o /dev/null
+
+// Check that we don't crash on this in the old re-mangler.
+// rdar://133333754
+
+struct S<T> where T: ~Copyable {
+  final class C {
+    let x = 27
+  }
+}
+