In the memo, which the Wall Street Journal said was sent to employees and investors of the fast-food chain, McDonald's targets October for a launch date. It also says tests of all-day breakfast in San Diego and Nashville have been "encouraging."

“Serving all-day breakfast is likely the number one request we hear from McDonald’s customers. We’re testing it out in a few markets to learn more about this possibility,” McDonald’s said in a statement to the Wall Street Journal.