NEW YORK – Former Cubs outfielder Marlon Byrd has been suspended 50 games by Major League Baseball after testing positive for a performance-enhancing substance.

Major League Baseball announced the suspension Monday and said Byrd tested positive for Tamoxifen.

Byrd is a free agent and will be placed on the restricted list for the duration of his suspension, which began immediately. He started the season with the Cubs and was dealt to the Red Sox on April 21. He was designated for assignment by Boston on June 9 and released four days later.