  Within the framework of the coalescence model based on the phase-space
distributions of protons and neutrons generated from the {{\tt iEBE-VISHNU}}
hybrid model with {{\tt AMPT}} initial conditions, we study the spectra and
elliptic flow of deuterons and helium-3 in relativistic heavy ion collisions at
the Relativistic Heavy Ion Collider (RHIC) and the Larger Hadron Collider
(LHC). Results from our model calculations for Au + Au collisions at
$\sqrt{s_{NN}}=200$ GeV at RHIC and Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$
TeV at the LHC are compared with available experimental data. Good agreements
are generally seen between theoretical results and experimental data, except
that the calculated yield of helium-3 in Pb + Pb collisions at
$\sqrt{s_{NN}}=2.76$ TeV underestimates the data by about a factor of two.
Possible reasons for these discrepancies are discussed. We also make
predictions on the spectra and elliptic flow of deuterons and helium-3 in Pb +
Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV that are being studied at LHC.
