  We present an orbifold GUT model in which the NMSSM Higgs trilinear couplings
are unified with the three Standard Model gauge couplings. The model is
constructed as an N=2 supersymmetric SU(8) gauge theory in six dimensions,
which is reduced to the NMSSM with extra U(1) factors upon compactification.
Such an unification is in good agreement with experiments. The predicted upper
limit for the lightest CP-even neutral Higgs boson is somewhat larger than in
the MSSM, and can be tested in the upcoming Large Hadron Collider.
