Portis has reportedly agreed to a two-year deal. The Bucks will be the 25-year-old's fourth different team of his career. He spent last season with the New York Knicks and averaged 10.1 points per game in 66 contests.
The 22nd-overall pick in 2015 signed a one-year deal with the Knicks in July 2019 that included a club option, which was declined by the team earlier this week.
Augustin, 33, is reported to have agreed to a three-year, $21-million contract. The veteran of 12 NBA seasons has played with the Orlando Magic since 2016 after signing a four-year deal with the team that off-season.
Suiting up in 57 regular-season games for the Magic in 2019-20, Augustin averaged 10.5 points and 4.6 assists per contest.