McMillan was scheduled to visit New England earlier this week.
Washington also had interest in McMillan, per Standig.
The Dolphins made McMillan a second-rounder in 2017, and Miami traded him to the Raiders last year. He was mostly a reserve while appearing in every game and finishing the year with 27 tackles and a forced fumble.
McMillan, 25, has appeared in 45 games with 32 starts. He has totaled 204 tackles, three pass breakups, three forced fumbles and nine tackles for loss.