Martin, 24, was a third-round pick of the San Francisco 49ers in 2014 and spent three seasons with the team, starting 24 games. He was claimed off waivers by the Cleveland Browns last March. He didn't play a snap for the team, however.
In Dallas, he'll likely fill a depth role with Travis Frederick locked in at center and Zack Martin holding down the right guard spot. The left guard spot is vacant, though right tackle La'el Collins could move back inside.