Martin, who turns 26 in August, spent last season with the 49ers after he was traded by the Miami Dolphins. He appeared in 15 games for the 49ers, starting nine. Martin was due $1.04 million in base salary for 2015.
According to ProFootballFocus.com, Martin allowed six sacks and 21 quarterback pressures last season, second and third-most on the 49ers, respectively.
In Miami, Martin gained national attention from the Richie Incognito/Dolphins bullying scandal. He spent two seasons with the Dolphins before the trade last March sent him to the 49ers in exchange for a conditional draft pick.
The Dolphins selected Martin in the second round of the 2012 NFL draft out of Stanford, where he played under former 49ers head coach Jim Harbaugh from 2008 to 2010. Harbaugh was the 49ers' coach from 2011 to 2014 before parting ways with the team this offseason and returning to his alma mater, Michigan.
- Mike Fiammetta