Cook pasta in a large pot of boiling salted water, stirring occasionally, until al dente; drain and transfer to a large bowl.
Meanwhile, heat oil in a frying pan or wide heavy saucepan over medium-high. Add garlic, then tomatoes, pepper, sugar, and 1 tsp. salt. Cook, stirring occasionally, until tomatoes burst and release their juices to form a sauce, 6–8 minutes.