Index: lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
+++ lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
@@ -81,10 +81,12 @@
   for (auto &It : OutContext.getSymbols()) {
     // Emit a .globaltype and .eventtype declaration.
     auto Sym = cast<MCSymbolWasm>(It.getValue());
-    if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_GLOBAL)
-      getTargetStreamer()->emitGlobalType(Sym);
-    else if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_EVENT)
-      getTargetStreamer()->emitEventType(Sym);
+    if (WebAssemblyTargetStreamer *TS = getTargetStreamer()) {
+      if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_GLOBAL)
+        TS->emitGlobalType(Sym);
+      else if (Sym->getType() == wasm::WASM_SYMBOL_TYPE_EVENT)
+        TS->emitEventType(Sym);
+    }
   }
 
   for (const auto &F : M) {
@@ -99,18 +101,20 @@
         Sym->setSignature(Signature.get());
         addSignature(std::move(Signature));
       }
-      // FIXME: this was originally intended for post-linking and was only used
-      // for imports that were only called indirectly (i.e. s2wasm could not
-      // infer the type from a call). With object files it applies to all
-      // imports. so fix the names and the tests, or rethink how import
-      // delcarations work in asm files.
-      getTargetStreamer()->emitIndirectFunctionType(Sym);
-
-      if (TM.getTargetTriple().isOSBinFormatWasm() &&
-          F.hasFnAttribute("wasm-import-module")) {
-        StringRef Name =
-            F.getFnAttribute("wasm-import-module").getValueAsString();
-        getTargetStreamer()->emitImportModule(Sym, Name);
+      if (WebAssemblyTargetStreamer *TS = getTargetStreamer()) {
+        // FIXME: this was originally intended for post-linking and was only
+        // used for imports that were only called indirectly (i.e. s2wasm
+        // could not infer the type from a call). With object files it applies
+        // to all imports. so fix the names and the tests, or rethink how
+        // import declarations work in asm files.
+        TS->emitIndirectFunctionType(Sym);
+
+        if (TM.getTargetTriple().isOSBinFormatWasm() &&
+            F.hasFnAttribute("wasm-import-module")) {
+          StringRef Name =
+              F.getFnAttribute("wasm-import-module").getValueAsString();
+          TS->emitImportModule(Sym, Name);
+        }
       }
     }
   }
@@ -165,19 +169,21 @@
   WasmSym->setSignature(Signature.get());
   addSignature(std::move(Signature));
 
-  // FIXME: clean up how params and results are emitted (use signatures)
-  getTargetStreamer()->emitParam(CurrentFnSym, ParamVTs);
+  if (WebAssemblyTargetStreamer *TS = getTargetStreamer()) {
+    // FIXME: clean up how params and results are emitted (use signatures)
+    TS->emitParam(CurrentFnSym, ParamVTs);
 
-  // Emit the function index.
-  if (MDNode *Idx = F.getMetadata("wasm.index")) {
-    assert(Idx->getNumOperands() == 1);
+    // Emit the function index.
+    if (MDNode *Idx = F.getMetadata("wasm.index")) {
+      assert(Idx->getNumOperands() == 1);
 
-    getTargetStreamer()->emitIndIdx(AsmPrinter::lowerConstant(
-        cast<ConstantAsMetadata>(Idx->getOperand(0))->getValue()));
-  }
+      TS->emitIndIdx(AsmPrinter::lowerConstant(
+          cast<ConstantAsMetadata>(Idx->getOperand(0))->getValue()));
+    }
 
-  getTargetStreamer()->emitResult(CurrentFnSym, ResultVTs);
-  getTargetStreamer()->emitLocal(MFI->getLocals());
+    TS->emitResult(CurrentFnSym, ResultVTs);
+    TS->emitLocal(MFI->getLocals());
+  }
 
   AsmPrinter::EmitFunctionBodyStart();
 }
Index: test/CodeGen/WebAssembly/null-streamer.ll
===================================================================
--- /dev/null
+++ test/CodeGen/WebAssembly/null-streamer.ll
@@ -0,0 +1,14 @@
+; RUN: llc -O0 -filetype=null -exception-model=wasm -mattr=+exception-handling < %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 @f(i8* %p)  {
+  call void @llvm.wasm.throw(i32 0, i8* %p)
+  call void @g()
+  ret i32 0
+}