This paper studies state synchronization of homogeneous continuous-time multi-agent systems (MAS) with time-varying communication topology in the presence of time-varying input delay. An upper bound for delay tolerance is obtained via a Lyapunov-Krasovskii functional-based method. This upper bound for the delay only depends on the agent dynamics and some rough information about the Laplacian matrix associated with the time-varying communication topology. For any delay satisfying this upper bound, a purely decentralized protocol based on a low-gain methodology is designed for each agent such that synchronization can be achieved without detailed knowledge about the network.