Index: include/llvm/Target/Target.td
===================================================================
--- include/llvm/Target/Target.td
+++ include/llvm/Target/Target.td
@@ -937,6 +937,14 @@
   // written register name matcher
   bit ShouldEmitMatchRegisterName = 1;
 
+  // Set to true if the target needs a generated 'alternative register name'
+  // matcher.
+  //
+  // This generates a function which can be used to lookup registers from
+  // their aliases. This function will fail when called on targets where
+  // several registers share the same alias (i.e. not a 1:1 mapping).
+  bit ShouldEmitMatchRegisterAltName = 0;
+
   // HasMnemonicFirst - Set to false if target instructions don't always
   // start with a mnemonic as the first token.
   bit HasMnemonicFirst = 1;
Index: utils/TableGen/AsmMatcherEmitter.cpp
===================================================================
--- utils/TableGen/AsmMatcherEmitter.cpp
+++ utils/TableGen/AsmMatcherEmitter.cpp
@@ -2225,6 +2225,37 @@
   OS << "}\n\n";
 }
 
+/// Emit the function to match a string to the target
+/// specific register enum.
+static void emitMatchRegisterAltName(CodeGenTarget &Target, Record *AsmParser,
+                                     raw_ostream &OS) {
+  // Construct the match list.
+  std::vector<StringMatcher::StringPair> Matches;
+  const auto &Regs = Target.getRegBank().getRegisters();
+  for (const CodeGenRegister &Reg : Regs) {
+
+    auto AltNames = Reg.TheDef->getValueAsListOfStrings("AltNames");
+
+    for (auto AltName : AltNames) {
+      AltName = StringRef(AltName).trim();
+
+      // don't handle empty alternative names
+      if (AltName.empty())
+        continue;
+
+      Matches.emplace_back(AltName,
+                           "return " + utostr(Reg.EnumValue) + ";");
+    }
+  }
+
+  OS << "static unsigned MatchRegisterAltName(StringRef Name) {\n";
+
+  StringMatcher("Name", Matches, OS).Emit();
+
+  OS << "  return 0;\n";
+  OS << "}\n\n";
+}
+
 static const char *getMinimalTypeForRange(uint64_t Range) {
   assert(Range <= 0xFFFFFFFFFFFFFFFFULL && "Enum too large");
   if (Range > 0xFFFFFFFFULL)
@@ -2756,6 +2787,9 @@
   if (AsmParser->getValueAsBit("ShouldEmitMatchRegisterName"))
     emitMatchRegisterName(Target, AsmParser, OS);
 
+  if (AsmParser->getValueAsBit("ShouldEmitMatchRegisterAltName"))
+    emitMatchRegisterAltName(Target, AsmParser, OS);
+
   OS << "#endif // GET_REGISTER_MATCHER\n\n";
 
   OS << "\n#ifdef GET_SUBTARGET_FEATURE_NAME\n";