Oller agreed to a minor-league contract with Miami on Tuesday, Ari Alexander of KPRC 2 in Houston reports.
Oller was released by the Guardians last week after posting a 7.48 ERA and 33:18 K:BB over 27.2 innings with Triple-A Columbus. The 29-year-old holds an ugly 7.09 ERA over 28 appearances (15 starts) at the major-league level, but he could get a shot eventually with the Marlins, perhaps after they unload assets at the trade deadline and need someone to fill innings.