diff --git a/utils/TableGen/AsmMatcherEmitter.cpp b/utils/TableGen/AsmMatcherEmitter.cpp
index 0d7c5ffbea1..d4a0616584b 100644
--- a/utils/TableGen/AsmMatcherEmitter.cpp
+++ b/utils/TableGen/AsmMatcherEmitter.cpp
@@ -460,6 +460,20 @@ struct MatchableInfo {
         TheDef->getValueAsBit("UseInstAsmMatchConverter")) {
   }
 
+  // Could remove this and the dtor if PointerUnion supported unique_ptr
+  // elements with a dynamic failure/assertion (like the one below) in the case
+  // where it was copied while being in an owning state.
+  MatchableInfo(const MatchableInfo &RHS)
+      : AsmVariantID(RHS.AsmVariantID), AsmString(RHS.AsmString),
+        TheDef(RHS.TheDef), DefRec(RHS.DefRec), ResOperands(RHS.ResOperands),
+        Mnemonic(RHS.Mnemonic), AsmOperands(RHS.AsmOperands),
+        RequiredFeatures(RHS.RequiredFeatures),
+        ConversionFnKind(RHS.ConversionFnKind),
+        HasDeprecation(RHS.HasDeprecation),
+        UseInstAsmMatchConverter(RHS.UseInstAsmMatchConverter) {
+    assert(!DefRec.is<const CodeGenInstAlias *>());
+  }
+
   ~MatchableInfo() {
     delete DefRec.dyn_cast<const CodeGenInstAlias*>();
   }