The Portugal international has joined the Lisbon giants for the 2013-14 campaign, having spent part of last season with Deportivo la Coruna
The 25-year-old joined the Rojiblancos from Braga in 2011, but spent the second half of season with fellow Liga outfit Deportivo la Coruna, who suffered relegation at the end of the campaign.
The Portugal international has now opted to move back to his homeland for the duration of the 2013-14 season, as he attempts to secure regular first-team football.
"Atletico Madrid and Benfica have reached an agreement for the loan of Silvio to the Lisbon team for the upcoming season," a statement read on Atletico's official website.
Silvio becomes the eight signing for Benfica this summer, following the likes of Lisandro Lopez and Miralem Sujlemani to the Estadio da Luz.