Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td	(revision 234484)
+++ include/clang/Basic/DiagnosticSemaKinds.td	(working copy)
@@ -468,6 +468,8 @@
     InGroup<Main>;
 def err_static_main : Error<"'main' is not allowed to be declared static">;
 def err_inline_main : Error<"'main' is not allowed to be declared inline">;
+def ext_variadic_main : ExtWarn<
+  "'main' is not allowed to be declared variadic">, InGroup<Main>;
 def ext_noreturn_main : ExtWarn<
   "'main' is not allowed to be declared _Noreturn">, InGroup<Main>;
 def note_main_remove_noreturn : Note<"remove '_Noreturn'">;
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp	(revision 234484)
+++ lib/Sema/SemaDecl.cpp	(working copy)
@@ -8262,6 +8262,12 @@
 
   bool HasExtraParameters = (nparams > 3);
 
+  if (FTP->isVariadic()) {
+    Diag(FD->getLocation(), diag::ext_variadic_main);
+    // FIXME: if we had information about the location of the ellipsis, we
+    // could add a FixIt hint to remove it as a parameter.
+  }
+
   // Darwin passes an undocumented fourth argument of type char**.  If
   // other platforms start sprouting these, the logic below will start
   // getting shifty.
Index: test/Sema/warn-main.c
===================================================================
--- test/Sema/warn-main.c	(revision 234484)
+++ test/Sema/warn-main.c	(working copy)
@@ -29,3 +29,5 @@
   return 0;
 }
 
+// expected-warning@+1 {{'main' is not allowed to be declared variadic}}
+int main(int argc, char**argv, ...) { return 0; }