Merriman, 28, had 39 1/2 sacks in his first three NFL seasons but injuries then limited his playing and he had five sacks since 2008 while playing in only 23 games.
He played the bulk of his career with the San Diego Chargers but joined the Bills in 2010 when they claimed him off waivers.
He was injured shortly after joining Buffalo and spent the rest of that season on injured reserve. He appeared in five games last season before Achilles tendon problems surfaced and he was again put in IR.
Merriman was the 12th overall selection by the 2005 draft by San Diego. He was named all-pro after the 2005, '06 and '07 seasons.