Portland had a four-game winning streak snapped, but the Trail Blazers made a game of it after trailing by 19 late in the first half.
A tip-in by Nicolas Batum ended a seven-point Portland run and brought the Trail Blazers within four with 44 seconds remaining.
Portland chose to play defense throughout the ensuing 24-second clock instead of fouling, but that strategy failed to work when Landry scored on a layup with 24.7 seconds to play.
That gave the Warriors a six-point lead, enough of a cushion to survive a 3-pointer by Damian Lillard with 22 seconds to go. Golden State then closed out the victory at the foul line.
Lillard made seven 3-pointers and scored 37 points -- eight more than he had produced in any other game this season.