Index: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
===================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
@@ -90,6 +90,10 @@
   return new WebAssemblyTargetAsmStreamer(S, OS);
 }
 
+static MCTargetStreamer *createNullTargetStreamer(MCStreamer &S) {
+  return new WebAssemblyTargetNullStreamer(S);
+}
+
 // Force static initialization.
 extern "C" void LLVMInitializeWebAssemblyTargetMC() {
   for (Target *T :
@@ -120,6 +124,8 @@
                                                  createObjectTargetStreamer);
     // Register the asm target streamer.
     TargetRegistry::RegisterAsmTargetStreamer(*T, createAsmTargetStreamer);
+    // Register the null target streamer.
+    TargetRegistry::RegisterNullTargetStreamer(*T, createNullTargetStreamer);
   }
 }
 
Index: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
===================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
@@ -88,6 +88,23 @@
   void emitImportModule(MCSymbolWasm *Sym, StringRef ModuleName) override;
 };
 
+/// This part is for null output
+class WebAssemblyTargetNullStreamer final : public WebAssemblyTargetStreamer {
+public:
+  explicit WebAssemblyTargetNullStreamer(MCStreamer &S)
+      : WebAssemblyTargetStreamer(S) {}
+
+  void emitParam(MCSymbol *Symbol, ArrayRef<MVT> Types) override {}
+  void emitResult(MCSymbol *Symbol, ArrayRef<MVT> Types) override {}
+  void emitLocal(ArrayRef<MVT> Types) override {}
+  void emitEndFunc() override {}
+  void emitIndirectFunctionType(MCSymbolWasm *Symbol) override {}
+  void emitIndIdx(const MCExpr *Value) override {}
+  void emitGlobalType(MCSymbolWasm *Sym) override {}
+  void emitEventType(MCSymbolWasm *Sym) override {}
+  void emitImportModule(MCSymbolWasm *Sym, StringRef ModuleName) override {}
+};
+
 } // end namespace llvm
 
 #endif
Index: llvm/trunk/test/CodeGen/WebAssembly/null-streamer.ll
===================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/null-streamer.ll
+++ llvm/trunk/test/CodeGen/WebAssembly/null-streamer.ll
@@ -0,0 +1,19 @@
+; RUN: llc < %s -O0 -filetype=null -exception-model=wasm -mattr=+exception-handling
+; RUN: llc < %s -O0 -filetype=asm -asm-verbose=false -exception-model=wasm -mattr=+exception-handling | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+declare void @llvm.wasm.throw(i32, i8*)
+declare void @g()
+
+define i32 @test(i8* %p)  {
+  %n = alloca i32
+  call void @llvm.wasm.throw(i32 0, i8* %p)
+  call void @g()
+  ret i32 0
+}
+
+; CHECK-DAG: .globaltype
+; CHECK-DAG: .eventtype
+; CHECK-DAG: .functype