  The formation histories of lithium-rich and carbon-rich red giants are not
yet understood. It has been proposed that the merger of a helium-core white
dwarf with a red giant branch star might provide a solution. We have computed
an extended grid of post-merger evolution models and combined these with
predictions of binary star population synthesis. The results strongly support
the proposal that the merger of a helium white dwarf with a red giant branch
star can provide the progenitors of both lithium-rich red clump stars and
early-R carbon stars. The distribution of post-merger models in $T_{\rm eff}$,
$\log g$, $\log L$, the surface abundances of lithium and carbon, and the
predicted space densities agree well with the observed distributions of these
parameters for Li-rich and early-R stars in the Galaxy.
