  We study spontaneous CP violation as a solution to the strong CP problem in
left-right symmetric theories. The discrete CP symmetry is broken by a complex
vacuum expectation value of a right-handed Higgs doublet. Heavy vectorlike
down-type quarks mix with the Standard Model quarks introducing the known CP
violation - realizing a variant of the Nelson-Barr mechanism. A nonvanishing
QCD vacuum angle is generated at loop level. The implementation in the
ultraviolet complete theory of trinification at low scales is discussed. We
further comment on the phenomenology and future testability of the model.
