  Cosmic-ray (CR) antihelium is an important observable for dark matter (DM)
indirect searches due to extremely low secondary backgrounds towards low
energies. In a given DM model, the predicted CR antihelium flux is expected to
be strongly correlated with that of CR antiprotons. In this work, we use the
AMS-02 $\bar p/p$ data to constrain the DM annihilation cross section, and the
ALICE data on the $^3\overline{\text{He}}$ and $\overline{\text{T}}$
productions to determine the parameters in the coalescence model for
anti-nucleus formation. The hadronic cross sections are estimated using
Monte-Carlo event generators including $\texttt{EPOS-LHC}$ and
$\texttt{DPMJET}$. Based on these constraints, we make predictions for the
maximal antihelium flux for typical DM annihilation final states, and perform a
detailed analysis on the uncertainties due to the DM density profiles and CR
propagation models. We find that the results are highly insensitive to both of
them, but still significantly depends on the hadronization models in event
generators. The prospects of detecting antihelium for the AMS-02 experiment is
discussed. We show that with very optimistic assumptions, CR
$^3\overline{\text{He}}$ is within the reach of the AMS-02 experiment. The
$^3\overline{\text{He}}$ events which can be detected by AMS-02 are likely to
have kinetic energy $T \gtrsim 30$~GeV, which is consistent with the
preliminary AMS-02 search results. The events which can be observed by AMS-02
are likely to arise dominantly from secondary backgrounds rather than DM
interactions.
