Index: lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
+++ lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
@@ -157,6 +157,8 @@
     return MVT::f32;
   if (RC == &WebAssembly::F64RegClass)
     return MVT::f64;
+  if (RC == &WebAssembly::V128RegClass)
+    return MVT::v16i8;
   if (RC == &WebAssembly::EXCEPT_REFRegClass)
     return MVT::ExceptRef;
   llvm_unreachable("unrecognized register class");
Index: test/CodeGen/WebAssembly/simd-arith.ll
===================================================================
--- test/CodeGen/WebAssembly/simd-arith.ll
+++ test/CodeGen/WebAssembly/simd-arith.ll
@@ -5,6 +5,10 @@
 ; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -mattr=-simd128 | FileCheck %s --check-prefixes CHECK,NO-SIMD128
 ; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -mattr=-simd128 -fast-isel | FileCheck %s --check-prefixes CHECK,NO-SIMD128
 
+; check that a non-test run (including explicit locals pass) at least finishes
+; RUN: llc < %s -O0 -wasm-enable-unimplemented-simd -mattr=+simd128,+sign-ext
+; RUN: llc < %s -O2 -wasm-enable-unimplemented-simd -mattr=+simd128,+sign-ext
+
 ; Test that basic SIMD128 arithmetic operations assemble as expected.
 
 target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"