Temporary Gravestone at Muhammad Ali's Burial Site

So many people are flocking to the gravesite where Muhammad Ali is buried, the cemetery has put up a temporary headstone to help guide fans to the right spot ... TMZ Sports has learned.

The headstone is a basic look -- the boxer's name etched in black stone.

Cemetery staffers say the stone will be replaced with a permanent one -- which is currently being made.

In the meantime, we're told there has been a "steady stream of fans" visiting the cemetery -- and to keep them from aimlessly wandering the grounds, the staff put down the temporary stone.

Ali died back in June -- no word on when the permanent stone will be completed.