Olynyk shot 9 for 9 from the field and 8 for 8 on free throws to go along with nine rebounds, and Harris had 10 boards for Gonzaga (18-2, 5-0), which was coming off a last-second loss at No. 9 Butler last weekend.
Josh Sharp and Brandon Davies led BYU (15-6, 5-2) with 14 points each. The Cougars scored just 21 points in the first half, and made only 35.6 percent of its shots from the field.
BYU's Tyler Haws, the WCC scoring leader at 21 points per game coming in, missed all nine of his shots from the field and was held to just one point. Haws had 42 points against Virginia Tech, the most by a Division I player this season. His previous low this season was nine points against Iowa State, and he had scored at least 20 in seven consecutive games coming in.
The Cougars next play at Portland Saturday night.