The Las Vegas Raiders have agreed with free agent linebacker Cory Littleton on a three-year contract. A person familiar with the contract says the sides came to agreement on the deal to give the Raiders a major upgrade at linebacker. The person spoke on condition of anonymity because the contract can’t be signed until the start of the new league year on Wednesday. NFL Network reported the contract is worth up to $36 million. Littleton is the second big free agent addition at linebacker for the Raiders, who have had a revolving door at the position in recent years. A second person said on condition of anonymity Monday that the team also agreed to a three-year deal with former Chicago linebacker Nick Kwiatkoski. The Raiders entered free agency with only one linebacker who started a game last year under contract in Marquel Lee. They have spent years trying to fill the position with mostly lower-round draft picks and bargain free agents. But coach Jon Gruden and general manager Mike Mayock are investing heavily in the position this offseason with two major additions to open free agency. Littleton is one of the best coverage linebackers in the league with the ability to match up with tight ends and running backs. Littleton’s 26 passes defensed are the most of any linebacker in the NFL over the past three seasons, according to SportRadar. The 26-year-old Littleton joined the Rams as an undrafted free agent out of Washington in 2016. After playing mostly on special teams his first two seasons, Littleton has became a fixture on the Rams defense in 2018. He started all 32 games the past two years with 259 tackles, 22 passes defensed, five interceptions, two forced fumbles, four fumble recoveries, 7 1/2 sacks and 15 tackles for loss.