Valdez was promoted from Triple-A Buffalo on Wednesday, Gregor Chisholm of MLB.com reports.
Valdez was brought up prior to Wednesday's game against the Red Sox due to Michael Bolsinger's placement on the disabled list with right knee inflammation. During six major-league appearances this year, Valdez has posted a 7.90 ERA with a 1.83 WHIP over the course of 13.2 innings. He will likely only be used in low-leverage situations while with the Blue Jays.