Index: lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
===================================================================
--- lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -367,6 +367,27 @@
     CurrentState = Label;
   }
 
+  bool ParseSignature(MCSymbolWasm *WasmSym) {
+    auto Signature = make_unique<wasm::WasmSignature>();
+    if (Expect(AsmToken::LParen, "("))
+      return true;
+    if (ParseRegTypeList(Signature->Params))
+      return true;
+    if (Expect(AsmToken::RParen, ")"))
+      return true;
+    if (Expect(AsmToken::MinusGreater, "->"))
+      return true;
+    if (Expect(AsmToken::LParen, "("))
+      return true;
+    if (ParseRegTypeList(Signature->Returns))
+      return true;
+    if (Expect(AsmToken::RParen, ")"))
+      return true;
+    WasmSym->setSignature(Signature.get());
+    addSignature(std::move(Signature));
+    return false;
+  }
+
   // This function processes wasm-specific directives streamed to
   // WebAssemblyTargetStreamer, all others go to the generic parser
   // (see WasmAsmParser).
@@ -422,28 +443,25 @@
         // This .functype indicates a start of a function.
         CurrentState = FunctionStart;
       }
-      auto Signature = make_unique<wasm::WasmSignature>();
-      if (Expect(AsmToken::LParen, "("))
-        return true;
-      if (ParseRegTypeList(Signature->Params))
-        return true;
-      if (Expect(AsmToken::RParen, ")"))
-        return true;
-      if (Expect(AsmToken::MinusGreater, "->"))
-        return true;
-      if (Expect(AsmToken::LParen, "("))
-        return true;
-      if (ParseRegTypeList(Signature->Returns))
+      if (ParseSignature(WasmSym))
         return true;
-      if (Expect(AsmToken::RParen, ")"))
-        return true;
-      WasmSym->setSignature(Signature.get());
-      addSignature(std::move(Signature));
       WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
       TOut.emitFunctionType(WasmSym);
       // TODO: backend also calls TOut.emitIndIdx, but that is not implemented.
       return Expect(AsmToken::EndOfStatement, "EOL");
 
+    } else if (DirectiveID.getString() == ".eventtype") {
+      auto SymName = ExpectIdent();
+      if (SymName.empty()) return true;
+      auto WasmSym = cast<MCSymbolWasm>(
+                    TOut.getStreamer().getContext().getOrCreateSymbol(SymName));
+      if (ParseSignature(WasmSym))
+        return true;
+      WasmSym->setType(wasm::WASM_SYMBOL_TYPE_EVENT);
+      TOut.emitEventType(WasmSym);
+      // TODO: backend also calls TOut.emitIndIdx, but that is not implemented.
+      return Expect(AsmToken::EndOfStatement, "EOL");
+
     } else if (DirectiveID.getString() == ".local") {
       if (CurrentState != FunctionStart)
         return Error(".local directive should follow the start of a function",
Index: lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
===================================================================
--- lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
+++ lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.h
@@ -54,6 +54,7 @@
 /// This part is for ascii assembly output
 class WebAssemblyTargetAsmStreamer final : public WebAssemblyTargetStreamer {
   formatted_raw_ostream &OS;
+  void emitSignature(const MCSymbolWasm *Sym);
 
 public:
   WebAssemblyTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS);
Index: lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
===================================================================
--- lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
+++ lib/Target/WebAssembly/MCTargetDesc/WebAssemblyTargetStreamer.cpp
@@ -61,23 +61,30 @@
 
 void WebAssemblyTargetAsmStreamer::emitEndFunc() { OS << "\t.endfunc\n"; }
 
-void WebAssemblyTargetAsmStreamer::emitFunctionType(const MCSymbolWasm *Sym) {
-  assert(Sym->isFunction());
-  OS << "\t.functype\t" << Sym->getName() << " (";
+void WebAssemblyTargetAsmStreamer::emitSignature(const MCSymbolWasm *Sym) {
+  OS << " (";
   auto &Params = Sym->getSignature()->Params;
   for (auto &Ty : Params) {
-    if (&Ty != &Params[0]) OS << ", ";
+    if (&Ty != &Params[0])
+      OS << ", ";
     OS << WebAssembly::TypeToString(Ty);
   }
   OS << ") -> (";
   auto &Returns = Sym->getSignature()->Returns;
   for (auto &Ty : Returns) {
-    if (&Ty != &Returns[0]) OS << ", ";
+    if (&Ty != &Returns[0])
+      OS << ", ";
     OS << WebAssembly::TypeToString(Ty);
   }
   OS << ")\n";
 }
 
+void WebAssemblyTargetAsmStreamer::emitFunctionType(const MCSymbolWasm *Sym) {
+  assert(Sym->isFunction());
+  OS << "\t.functype\t" << Sym->getName();
+  emitSignature(Sym);
+}
+
 void WebAssemblyTargetAsmStreamer::emitGlobalType(const MCSymbolWasm *Sym) {
   assert(Sym->isGlobal());
   OS << "\t.globaltype\t" << Sym->getName() << ", " <<
@@ -89,16 +96,7 @@
 void WebAssemblyTargetAsmStreamer::emitEventType(const MCSymbolWasm *Sym) {
   assert(Sym->isEvent());
   OS << "\t.eventtype\t" << Sym->getName();
-  if (Sym->getSignature()->Returns.empty())
-    OS << ", void";
-  else {
-    assert(Sym->getSignature()->Returns.size() == 1);
-    OS << ", "
-       << WebAssembly::TypeToString(Sym->getSignature()->Returns.front());
-  }
-  for (auto Ty : Sym->getSignature()->Params)
-    OS << ", " << WebAssembly::TypeToString(Ty);
-  OS << '\n';
+  emitSignature(Sym);
 }
 
 void WebAssemblyTargetAsmStreamer::emitImportModule(const MCSymbolWasm *Sym,
Index: test/CodeGen/WebAssembly/exception.ll
===================================================================
--- test/CodeGen/WebAssembly/exception.ll
+++ test/CodeGen/WebAssembly/exception.ll
@@ -262,4 +262,4 @@
 declare %struct.Cleanup* @_ZN7CleanupD1Ev(%struct.Cleanup* returned)
 
 ; CHECK: __cpp_exception:
-; CHECK: .eventtype  __cpp_exception, void, i32
+; CHECK: .eventtype  __cpp_exception (i32) -> ()
Index: test/MC/WebAssembly/basic-assembly.s
===================================================================
--- test/MC/WebAssembly/basic-assembly.s
+++ test/MC/WebAssembly/basic-assembly.s
@@ -8,6 +8,7 @@
 test0:
     # Test all types:
     .functype   test0 (i32, i64) -> (i32)
+    .eventtype  __cpp_exception (i32) -> ()
     .local      f32, f64, v128, v128
     # Explicit getlocal/setlocal:
     get_local   2
@@ -66,6 +67,7 @@
 # CHECK:           .text
 # CHECK-LABEL: test0:
 # CHECK-NEXT:      .functype test0 (i32, i64) -> (i32)
+# CHECK-NEXT:      .eventtype  __cpp_exception (i32) -> ()
 # CHECK-NEXT:      .local      f32, f64
 # CHECK-NEXT:      get_local   2
 # CHECK-NEXT:      set_local   2