We have performed a series of large-scale atomistic simulations of the Rayleigh-Taylor instability including up to 5.7 x 10(9) particles and spanning time and length scales of up to 170 ns and 45 microm , respectively. The results suggest that atomistic fluid dynamics simulations exhibit the same scaling as solutions of the continuum Navier-Stokes equations. Furthermore, a comparison with macroscopic Rayleigh-Taylor experiments suggests that the results of such atomistic simulations can, in fact, be scaled up to macroscopic dimensions, even for complex, nonstationary flows.