We've been studying the "tweed" precursors above the martensitic transition in shape-memory alloys. These characteristic cross-hatched modulations occur for hundreds of degrees above the first-order shape-changing transition. Our two-dimensional model for this transition, in the limit of infinite elastic anisotropy, can be mapped onto a spin-glass Hamiltonian in a random field. We suggest that the tweed precursors are a direct analogy of the spin-glass phase. The tweed is intermediate between the high-temperature cubic phase and the low-temperature martensitic phase in the same way as the spin-glass phase can be intermediate between ferromagnet and antiferromagnet.