Swendsen-Wang-type cluster dynamics is used in order to reduce relaxation time in spin-glass simulations. The shapes and sizes of the clusters are related to the local environment of the spins using dynamical information. For a Gaussian spin glass on a square lattice, the relaxation times are fitted by the Arrhenius form, exp(A/kT). The constant A for the cluster dynamics is found to be 5 times smaller than the one for conventional dynamics. We also obtain nu = 2.0 +/- 0.2.