According to CBS Sports he's done for the season.
from cbssports.com:
With training camp now underway, it's inevitable the injury bug would come a-calling. The Dallas Cowboys are hoping to dodge the latter in all ways possible, but the first official scare is already here, and it arrived on the first day of padded practice. Gerald McCoy, one of the All-Pro defensive linemen who signed with the club in free agency, went down on Monday with what's being described as an apparent leg injury. The severity of the issue is currently unknown, but a source tells CBS Sports an MRI was to be done on McCoy's leg as early as Monday afternoon -- to determine the severity and specificity of the injury.
That has now occurred and it's the worst-case scenario for the Cowboys.
McCoy has suffered a torn quadricep in his right leg, the team announced, and will undergo season-ending surgery. He will now head to injured reserve, and it's not yet determined how the team will utilize his vacated seat on the roster.
McCoy joined the Cowboys on a three-year deal worth $18.3 million, a financial nod to how Mike McCarthy plans to utilize him in 2020, which is to say quite a bit. For his part, the six-time Pro Bowl pass rusher is looking forward to just that, noting how his final year with the Carolina Panthers left him starved for snaps.