We present Chipyard - an open-source integrated SoC design, simulation, and implementation environment for specialized RISC-V compute systems. Continued improvement in computing efficiency requires functional specialization of hardware designs. Chipyard includes configurable, composable, open-source, generator-based IP blocks that can be used across multiple stages of the hardware development flow while maintaining design intent and integration consistency. Through cloud-hosted FPGA simulation and rapid ASIC implementation, this work allows for continuous validation of physically realizable customized systems. We demonstrate the capabilities of the Chipyard framework using the BEAGLE test-chip, a heterogenous SoC composed of anapplication class open-source Linux-capable BOOM out-of-order core connected toa vector accelerator and an in-order Rocket corec onnected to a systolic-array machine learning accelerator.