The Rio Ave striker has scored 11 goals in 27 games for his team this season.
Taremi, 27, arrived at Rio Ave from Al Gharafa, Qatar at the beginning of the season. He has since imposed himself as one of the main options for coach Carlos Carvalhal.
Porto, another well-known Poruguese team, had already shown an interest in signing Taremi.
Helton Leite, goalkeeper of Boavista, is another player whom Benfica is going to sign.