Index: wasm/Driver.cpp
===================================================================
--- wasm/Driver.cpp
+++ wasm/Driver.cpp
@@ -292,10 +292,11 @@
 
   Config->AllowUndefined = Args.hasArg(OPT_allow_undefined);
   Config->EmitRelocs = Args.hasArg(OPT_emit_relocs);
-  Config->Entry = Args.getLastArgValue(OPT_entry);
+  Config->Relocatable = Args.hasArg(OPT_relocatable);
+  Config->Entry = Args.getLastArgValue(OPT_entry,
+                                       Config->Relocatable ? "" : "_start");
   Config->ImportMemory = Args.hasArg(OPT_import_memory);
   Config->OutputFile = Args.getLastArgValue(OPT_o);
-  Config->Relocatable = Args.hasArg(OPT_relocatable);
   Config->SearchPaths = getArgs(Args, OPT_L);
   Config->StripAll = Args.hasArg(OPT_strip_all);
   Config->StripDebug = Args.hasArg(OPT_strip_debug);
@@ -323,9 +324,8 @@
     error("entry point specified for relocatable output file");
 
   if (!Config->Relocatable) {
-    if (Config->Entry.empty())
-      Config->Entry = "_start";
-    addSyntheticUndefinedFunction(Config->Entry);
+    if (!Config->Entry.empty())
+      addSyntheticUndefinedFunction(Config->Entry);
 
     addSyntheticGlobal("__stack_pointer", 0);
   }
@@ -348,6 +348,8 @@
 
   if (!Config->Entry.empty()) {
     Symbol *Sym = Symtab->find(Config->Entry);
+    if (!Sym)
+      fatal("entry point not found: " + Config->Entry);
     if (!Sym->isFunction())
       fatal("entry point is not a function: " + Sym->getName());
   }
Index: wasm/Writer.cpp
===================================================================
--- wasm/Writer.cpp
+++ wasm/Writer.cpp
@@ -305,22 +305,6 @@
     writeExport(OS, MemoryExport);
   }
 
-  if (ExportMain) {
-    Symbol *Sym = Symtab->find(Config->Entry);
-    if (Sym->isDefined()) {
-      if (!Sym->isFunction())
-        fatal("entry point is not a function: " + Sym->getName());
-
-      if (!ExportOther) {
-        WasmExport MainExport;
-        MainExport.Name = Config->Entry;
-        MainExport.Kind = WASM_EXTERNAL_FUNCTION;
-        MainExport.Index = Sym->getOutputIndex();
-        writeExport(OS, MainExport);
-      }
-    }
-  }
-
   if (ExportOther) {
     for (ObjFile *File : Symtab->ObjectFiles) {
       for (Symbol *Sym : File->getSymbols()) {
@@ -345,7 +329,22 @@
   }
 }
 
-void Writer::createStartSection() {}
+void Writer::createStartSection() {
+  if (Config->Entry.empty())
+    return;
+
+  const Symbol *Sym = Symtab->find(Config->Entry);
+  if (!Sym)
+    fatal("entry point not found: " + Config->Entry);
+  if (!Sym->isFunction())
+    fatal("entry point is not a function: " + Sym->getName());
+
+  SyntheticSection *Section = createSyntheticSection(WASM_SEC_START);
+  raw_ostream &OS = Section->getStream();
+
+  log("Start: " + Sym->getName());
+  writeUleb128(OS, Sym->getOutputIndex(), "start index");
+}
 
 void Writer::createElemSection() {
   if (!NumElements)