  In this paper we derive the full set of differential equations and some
algebraic relations for p-forms constructed from type IIB Killing spinors.
These equations are valid for the most general type IIB supersymmetric
backgrounds which have a non-zero NS-NS 3-form field strength, H, and non-zero
R-R field strengths, G^{(1)}, G^{(3)} and G^{(5)}. Our motivation is to use
these equations to obtain generalised calibrations for branes in supersymmetric
backgrounds. In particular, we consider giant gravitons in AdS_5 x S^5. These
non-static branes have an interesting construction via holomorphic surfaces in
C^{1,2} x C^3. We construct the p-forms corresponding to these branes and show
that they satisfy the correct differential equations. Moreover, we interpret
the equations as calibration conditions and derive the calibration bound. We
find that giant gravitons minimise ``energy minus momentum''.
