The team did not disclose the details of Ellis' contract, but NFL Network's Ian Rapoport reported the deal is worth up to $15 million and includes more than $6 million in guaranteed money.
Ellis was scheduled to become an unrestricted free agent. He started 14 of the 16 games he played in 2017 and recorded career-highs in tackles (44) and sacks (0.5).
Ellis, 27, has spent all four of his NFL seasons with the Raiders.
Newhouse appeared in 14 games in his only season with the Raiders in 2017. He also dealt with injuries to his foot, hip and quadriceps.
According to Pro Football Focus, Newhouse was ranked 65th among 81 offensive tackles the website evaluated.
Newhouse joined the Raiders on a two-year, $3.55 million deal. He was set to make $1.55 million in 2018 and could have made a bonus of $200,000.