Index: test/wasm/data-layout.ll
===================================================================
--- test/wasm/data-layout.ll
+++ test/wasm/data-layout.ll
@@ -1,6 +1,6 @@
 ; RUN: llc -filetype=obj %p/Inputs/hello.ll -o %t.hello.o
 ; RUN: llc -filetype=obj %s -o %t.o
-; RUN: lld -flavor wasm --emit-relocs --allow-undefined --entry '' -o %t.wasm %t.o %t.hello.o
+; RUN: lld -flavor wasm --emit-relocs --allow-undefined --no-entry -o %t.wasm %t.o %t.hello.o
 ; RUN: obj2yaml %t.wasm | FileCheck %s
 
 target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
Index: wasm/Config.h
===================================================================
--- wasm/Config.h
+++ wasm/Config.h
@@ -10,6 +10,7 @@
 #ifndef LLD_WASM_CONFIG_H
 #define LLD_WASM_CONFIG_H
 
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/BinaryFormat/Wasm.h"
@@ -34,7 +35,7 @@
   uint32_t InitialMemory;
   uint32_t MaxMemory;
   uint32_t ZStackSize;
-  llvm::StringRef Entry;
+  llvm::Optional<llvm::StringRef> Entry;
   llvm::StringRef OutputFile;
   llvm::StringRef Sysroot;
 
Index: wasm/Driver.cpp
===================================================================
--- wasm/Driver.cpp
+++ wasm/Driver.cpp
@@ -219,6 +219,16 @@
     error("no input files");
 }
 
+static Optional<StringRef> getEntry(opt::InputArgList &Args,
+                                    Optional<StringRef> def) {
+  auto *Arg = Args.getLastArg(OPT_entry, OPT_no_entry);
+  if (!Arg)
+    return def;
+  if (Arg->getOption().getID() == OPT_no_entry)
+    return Optional<StringRef>();
+  return Optional<StringRef>(Arg->getValue());
+}
+
 void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
   WasmOptTable Parser;
   opt::InputArgList Args = Parser.parse(ArgsArr.slice(1));
@@ -248,8 +258,8 @@
       Args.hasFlag(OPT_check_signatures, OPT_no_check_signatures, false);
   Config->EmitRelocs = Args.hasArg(OPT_emit_relocs);
   Config->Relocatable = Args.hasArg(OPT_relocatable);
-  Config->Entry = Args.getLastArgValue(OPT_entry,
-                                       Config->Relocatable ? "" : "_start");
+  Config->Entry = getEntry(Args, Config->Relocatable ? Optional<StringRef>()
+                               : Optional<StringRef>(StringRef("_start")));
   Config->ImportMemory = Args.hasArg(OPT_import_memory);
   Config->OutputFile = Args.getLastArgValue(OPT_o);
   Config->SearchPaths = args::getStrings(Args, OPT_L);
@@ -276,20 +286,25 @@
   if (!Args.hasArg(OPT_INPUT))
     error("no input files");
 
-  if (Config->Relocatable && !Config->Entry.empty())
+  if (Config->Relocatable && Config->Entry)
     error("entry point specified for relocatable output file");
   if (Config->Relocatable && Args.hasArg(OPT_undefined))
     error("undefined symbols specified for relocatable output file");
 
   if (!Config->Relocatable) {
-    if (!Config->Entry.empty()) {
+    if (Config->Entry) {
+      if (Config->Entry.getValue().empty())
+        error("empty string invalid for entry point");
       static WasmSignature Signature = {{}, WASM_TYPE_NORESULT};
-      addSyntheticUndefinedFunction(Config->Entry, &Signature);
+      addSyntheticUndefinedFunction(Config->Entry.getValue(), &Signature);
     }
 
     // Handle the `--undefined <sym>` options.
-    for (StringRef S : args::getStrings(Args, OPT_undefined))
+    for (StringRef S : args::getStrings(Args, OPT_undefined)) {
+      if (S.empty())
+        error("empty string invalid for undefined symbol");
       addSyntheticUndefinedFunction(S, nullptr);
+    }
 
     addSyntheticGlobal("__stack_pointer", 0);
   }
@@ -310,10 +325,10 @@
       return;
   }
 
-  if (!Config->Entry.empty()) {
-    Symbol *Sym = Symtab->find(Config->Entry);
-    if (!Sym->isFunction())
-      fatal("entry point is not a function: " + Sym->getName());
+  if (Config->Entry) {
+    Symbol *Sym = Symtab->find(Config->Entry.getValue());
+    if (!Sym->isDefined())
+      error("entry point not found: " + Config->Entry.getValue());
   }
   for (StringRef S : args::getStrings(Args, OPT_undefined)) {
     Symbol *Sym = Symtab->find(S);
Index: wasm/Options.td
===================================================================
--- wasm/Options.td
+++ wasm/Options.td
@@ -68,6 +68,9 @@
 def entry: S<"entry">, MetaVarName<"<entry>">,
   HelpText<"Name of entry point symbol">;
 
+def no_entry: F<"no-entry">,
+  HelpText<"Do not output any entry point">;
+
 def error_limit: J<"error-limit=">,
   HelpText<"Maximum number of errors to emit before stopping (0 = no limit)">;
 
Index: wasm/Writer.cpp
===================================================================
--- wasm/Writer.cpp
+++ wasm/Writer.cpp
@@ -261,7 +261,8 @@
   bool ExportMemory = !Config->Relocatable && !Config->ImportMemory;
   bool ExportOther = true; // ??? TODO Config->Relocatable;
   bool ExportHidden = Config->Relocatable;
-  Symbol *EntrySym = Symtab->find(Config->Entry);
+  Symbol *EntrySym = Config->Entry ? Symtab->find(Config->Entry.getValue())
+                                   : nullptr;
   bool ExportEntry = !Config->Relocatable && EntrySym && EntrySym->isDefined();
 
   uint32_t NumExports = 0;
@@ -304,7 +305,7 @@
 
   if (ExportEntry) {
     WasmExport EntryExport;
-    EntryExport.Name = Config->Entry;
+    EntryExport.Name = Config->Entry.getValue();
     EntryExport.Kind = WASM_EXTERNAL_FUNCTION;
     EntryExport.Index = EntrySym->getOutputIndex();
     writeExport(OS, EntryExport);
@@ -334,10 +335,10 @@
 }
 
 void Writer::createStartSection() {
-  if (Config->Entry.empty())
+  if (!Config->Entry)
     return;
 
-  const Symbol *Sym = Symtab->find(Config->Entry);
+  const Symbol *Sym = Symtab->find(Config->Entry.getValue());
   assert(Sym && Sym->isDefined() && Sym->isFunction());
 
   SyntheticSection *Section = createSyntheticSection(WASM_SEC_START);