The Diamondbacks are expected to option Morillo to Triple-A Reno on Wednesday, Nick Piecoro of the Arizona Republic reports.
Morillo has made 28 relief appearances for the Diamondbacks this season, posting a 4.01 ERA and 25:13 K:BB across 24.2 frames. He'll be replaced on the roster by Jake Woodford, who will offer the Arizona bullpen more length.