"They gave me an opportunity and hopefully I can make them look good on it," LeBlanc said. "I'm going to enjoy the ride and try to do the best I can."
LeBlanc replaces Brad Peacock on the 25-man roster. Peacock was sent to Triple-A Oklahoma City on Saturday night -- following the Astros' 7-2 loss to the Royals -- to work as a starter.
"[LeBlanc] will add quality depth to our bullpen," Porter said. "He's a true left-handed long guy who has the ability to start."
Robert Falkoff is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.