Index: utils/TableGen/AsmMatcherEmitter.cpp
===================================================================
--- utils/TableGen/AsmMatcherEmitter.cpp
+++ utils/TableGen/AsmMatcherEmitter.cpp
@@ -438,12 +438,17 @@
   /// If this instruction is deprecated in some form.
   bool HasDeprecation;
 
+  /// If this matchable was generated from and InstAlias.
+  bool IsInstAlias;
+
   MatchableInfo(const CodeGenInstruction &CGI)
-    : AsmVariantID(0), AsmString(CGI.AsmString), TheDef(CGI.TheDef), DefRec(&CGI) {
+    : AsmVariantID(0), AsmString(CGI.AsmString), TheDef(CGI.TheDef), DefRec(&CGI),
+      IsInstAlias(false) {
   }
 
   MatchableInfo(std::unique_ptr<const CodeGenInstAlias> Alias)
-    : AsmVariantID(0), AsmString(Alias->AsmString), TheDef(Alias->TheDef), DefRec(Alias.release()) {
+    : AsmVariantID(0), AsmString(Alias->AsmString), TheDef(Alias->TheDef),
+      DefRec(Alias.release()), IsInstAlias(true) {
   }
 
   ~MatchableInfo() {
@@ -1749,7 +1754,7 @@
     // Check if we have a custom match function.
     std::string AsmMatchConverter =
       II->getResultInst()->TheDef->getValueAsString("AsmMatchConverter");
-    if (!AsmMatchConverter.empty()) {
+    if (!AsmMatchConverter.empty() && !II->IsInstAlias) {
       std::string Signature = "ConvertCustom_" + AsmMatchConverter;
       II->ConversionFnKind = Signature;