Multi-Messenger Astrophysics (MMA) brings together communities working in astrophysics, gravitational wave science and particle physics. Progress in real-time MMA requires reliable, performant and scalable cyberinfrastructure that 1) connects experiments and researchers at low latency to remove communications barriers, 2) enables immediate data analysis as information is received, and 3) provides tools to coordinate observational follow-up and data sharing that takes ownership, embargo periods, and intellectual/project credit into account. The SCIMMA collaboration is working with the MMA community to prototype the cyberinfrastructure tools it needs and to conceptualize the organization necessary to ensure sustainability. We will discuss two key cyberinfrastructure products we have prototyped: a next-generated publish-subscribe system, SCIMMA Hopskotch, and an integration of Identity and Access Management systems into MMA cyberinfrastructure.