Index: lib/CodeGen/MIRParser/MIParser.cpp
===================================================================
--- lib/CodeGen/MIRParser/MIParser.cpp
+++ lib/CodeGen/MIRParser/MIParser.cpp
@@ -1002,12 +1002,20 @@
 }
 
 bool MIParser::parseRegisterClassOrBank(VRegInfo &RegInfo) {
+  // It is possible a register class or register bank name can be in the form of
+  // integer of scalar type (e.g. i32). Fix token kind in that case.
+  auto Range = Token.range();
+  if (Token.isNot(MIToken::underscore) &&
+      (PFS.Names2RegClasses.find(Range) != PFS.Names2RegClasses.end() ||
+       PFS.Names2RegBanks.find(Range) != PFS.Names2RegBanks.end()))
+    Token.reset(MIToken::Identifier, Range).setStringValue(Range);
+
   if (Token.isNot(MIToken::Identifier) && Token.isNot(MIToken::underscore))
     return error("expected '_', register class, or register bank name");
   StringRef::iterator Loc = Token.location();
-  StringRef Name = Token.stringValue();
 
   // Was it a register class?
+  StringRef Name = Token.stringValue();
   auto RCNameI = PFS.Names2RegClasses.find(Name);
   if (RCNameI != PFS.Names2RegClasses.end()) {
     lex();
Index: test/CodeGen/MIR/WebAssembly/int-type-register-class-name.mir
===================================================================
--- /dev/null
+++ test/CodeGen/MIR/WebAssembly/int-type-register-class-name.mir
@@ -0,0 +1,13 @@
+# RUN: llc -mtriple=wasm32-unknown-unknown-wasm -run-pass none -o - %s | FileCheck %s
+# When a register class has a name of an integer type (i32)
+---
+name: regclass_name_test
+liveins:
+  - { reg: '$arguments' }
+body: |
+  bb.0:
+    liveins: $arguments
+    %0:i32 = CONST_I32 0, implicit-def dead $arguments
+    ; CHECK: %0:i32 = CONST_I32 0, implicit-def dead $arguments
+    RETURN_VOID implicit-def dead $arguments
+...
Index: test/CodeGen/MIR/WebAssembly/lit.local.cfg
===================================================================
--- /dev/null
+++ test/CodeGen/MIR/WebAssembly/lit.local.cfg
@@ -0,0 +1,2 @@
+if not 'WebAssembly' in config.root.targets:
+    config.unsupported = True