Reilly could have become a restricted free agent on July 1.
The 25-year-old defenseman had 11 points (three goals, eight assists) in 57 games for the Canadiens this season. Montreal acquired Reilly in a trade with the Minnesota Wild on March 26, 2018 and he had an NHL career-high 18 points (two goals, 16 assists) in 57 games with the Wild and Canadiens in 2017-18.
Reilly has 37 points (seven goals, 30 assists) in 160 NHL games with the Wild and Canadiens. He was selected by the Columbus Blue Jackets in the fourth round (No. 97) in the 2011 NHL Draft but opted not to sign and played three seasons at the University of Minnesota. He became a free agent and signed with the Wild on July 1, 2015.