Interlayer van der Waals (vdW) coupling is ubiquitous in two-dimensional materials. The authors explore these interactions in the cuprate (Bi, Pb)(Sr,La)CuO, revealing ultra-low energy phonon modes similar to graphene and transition metal dichalcogenides. Using high-resolution inelastic hard x-ray scattering and first-principles simulations, they reveal vdW phonons from the shear motion of adjacent Bi-O layers. These findings deepen our understanding of the vibrational properties of cuprates and suggest opportunities for the design of novel heterostructures. These results highlight the generic nature of vdW modes in layered materials, including doped copper oxides, and provide insights for future materials design and research.