This paper presents a new approach to hierarchical high-level synthesis with respect to internal register-transfer structures of complex components. Entire subdesigns can efficiently be used as complex components at a higher hierarchical level of the design. After synthesis, the calculated schedule of each subdesign is added to its register-transfer component model. This enables the sharing of unused subcomponents across different hierarchical levels of the design. Especially, subcomponents of autonomous components, with a separate controller, can also be shared. As a result, the presented methodology offers a high degree of optimization to hierarchically specified designs.