To speed up electromagnetic wave propagation simulations using the meshless time-domain method (MTDM) in complex shaped domains, this paper presents a strategy for embedding the modified radial point interpolation method (MRPIM)-based shape functions to MTDM, while maintaining the stability of the simulations. Numerical experiments show that, by using the strategy with appropriate parameters, the stability of the simulations using MTDM with MRPIM-based shape functions (MRPIM-MTDM) is considerably improved. In addition, the approach of the amplification/damping rate to convergence in MRPIM-MTDM is almost the same as that in the conventional MTDM. Furthermore, the total computation time of MRPIM-MTDM is less than that of the conventional MTDM.