Weems was claimed off waivers by the Diamondbacks on Monday.
The right-hander was designated for assignment by the Athletics on Saturday, and he should join the Diamondbacks' major-league bullpen after left-hander Ryan Buchter was designated for assignment in a corresponding move. Weems had been with Triple-A Las Vegas since mid-May, and he posted a 7.36 ERA and 1.62 WHIP in 14.2 innings across 15 relief appearances.