Defensive lineman Arik Armstead is signing a 3-year, $51 million contract with the Jacksonville Jaguars, a source told ESPN's Adam Schefter.

The San Francisco 49ers released Armstead on Wednesday after he and the team failed to work out a restructured contract.

He is coming off a season in which he played in 12 games with 27 tackles and five sacks for the NFC champion 49ers.

He also is coming off a torn meniscus in his right knee, an injury he suffered in a Dec. 3 win at the Philadelphia Eagles. Armstead finished that game after suffering the injury on the second play, but he did not play again until the Jan. 20 NFC divisional round win against the visiting Green Bay Packers.

Armstead, 30, appeared in all three of San Francisco's playoff games, posting 11 tackles, a sack, 7 quarterback pressures and a fumble recovery on 148 snaps. He said in February that while knee surgery will require a lengthy recovery, his hope is to be ready to return sometime in late July or August as training camps get underway.

San Francisco originally used the No. 17 pick in the 2015 NFL draft on Armstead. He began his career as a defensive end, but after dealing with myriad injuries early in his career, he transitioned into an interior role in 2019. A breakout 10-sack season that year helped him land a five-year, $85 million deal early in 2020 free agency.

Over nine seasons in San Francisco, Armstead played in 116 regular-season games, posting 33.5 career sacks. He also has appeared in 12 postseason games, registering eight sacks.

Armstead was not only San Francisco's longest-tenured player, he has been a philanthropic staple in the Bay Area and in his hometown of Sacramento. For the past four years, he has been the Niners' nominee for the Walter Payton NFL Man of the Year Award.

ESPN's Nick Wagoner contributed to this report.