Lyles, 2-7 with a 5.02 ERA, pitched five innings and allowed two earned runs in Houston's 7-5 win over San Francisco on Saturday night. Lyles has pitched 148 2-3 innings this season, and the Astros consider 160 to 170 innings a safe range for the rookie.
The move was announced Sunday.
Schafer has been on the DL since July 20 because of a left middle finger joint injury. He went 5-for-5 at Oklahoma City on Saturday and is expected to be activated on Monday.
Wade said Lyles would return to the Astros in September and pitch out of the bullpen.