In this talk, I will introduce a valence-bond dynamical mean-field theory of doped Mott insulators. It is based on a minimal cluster of two orbitals, each associated with a different region of momentum space and hybridized to a self-consistent bath. The low-doping regime is characterized by singlet formation and the suppression of quasiparticles in the antinodal regions, leading to the formation of Fermi arcs. I will show that this is described by an orbital-selective transition in momentum space. I will also present calculations for the tunneling and photoemission spectra that are consistent with the phenomenology of the normal state of cuprate superconductors.