Per ESPN's Dan Graziano, the Raiders are planning to release Bryant as of the 4 p.m. ET deadline for final roster cuts.
Per NFL Network's Ian Rapoport and Mike Garafolo, Bryant's release comes as he faces another suspension from the league for violating the substance abuse policy.
Michael Gehlken of the Las Vegas Review-Journal reported in June that the Raiders were concerned Bryant might be suspended for what was "believed to pertain to the NFL's substance-abuse policy."
The NFL suspended Bryant for the entire 2016 season for multiple violations of the policy. He was conditionally reinstated in April 2017 and appeared in 15 games last season with the Pittsburgh Steelers.
As part of Bryant's reinstatement last year, Rapoport noted the receiver had to work with a treating clinician who planned activities during the bye week and offseason.
The Raiders acquired Bryant from the Steelers during April's draft for a 2018 third-round draft pick. The 26-year-old has 126 receptions, 1,917 yards and 17 touchdowns in three seasons.