If and are analytic functions in the unit disc we define . If is bounded then the integral operator is bounded on the Bloch space, on the Dirichlet space, and on . We show that is norm-attaining on the Bloch space and on for any bounded analytic function , but does not attain its norm on the Dirichlet space for non-constant . Some results are also obtained for on the little Bloch space, and for another integral operator from the Dirichlet space to the Bergman space.