In a corresponding move, the Bills waived defensive tackle Marquavius Lewis with an injury designation.
Havili, signed by the Chargers as an undrafted free agent out of Eastern Washington this year, made 12 sacks during his college career, including seven as a senior. He set a freshman school record with 61 tackles.
Lewis, who signed by Buffalo last year as an undrafted free agent out of South Carolina, made 93 tackles in his last two college seasons. He spent parts of last season on the Bills' practice squad.