United paid Vitoria de Guimaraes £7.4million for the striker in 2010, but he only started three games - all in the cup competitions.
The 24-year-old, who made seven appearances in total, never looked like making it into the United first team and he was shipped out on loan to Besiktas, Rio Ave and Pacos de Ferreira.
On Friday, Benfica confirmed they had bought the player, releasing a statement on their website which read: "Bebe has signed an agreement with SL Benfica for four years."
Source : PA
Source: PA