Reinforced concrete (RC) walls are a commonly used lateral load-resisting system in many regions with high seismic hazard. Walls in buildings constructed prior to the implementation of ductile design principles may be susceptible to brittle strength degradation associated with diagonal tension, premature bar buckling, or lap-splice failures. Externally bonded fiber reinforced composites can be employed to prevent or delay those types of failures, but their effectiveness in improving the seismic response of walls has not been studied as extensively as for columns or beams. This paper presents an efficient computational modeling approach to analytically study the seismic response of RC walls retrofitted with fiber reinforced polymer (FRP) overlays. In this scheme, the walls are modeled using shell macroelements based on the nonlinear truss analogy for RC. Each macroelement consists of an assembly of horizontal, vertical, and diagonal truss elements with uniaxial stress-strain laws for concrete and steel. FRP overlays are modeled using shell elements superposed to the wall macroelements, and interface elements are employed to describe the bond between the FRP and the substrate. The modeling approach is used to reproduce a laboratory test recently conducted on a retrofitted RC wall with a barbell section. The web of the wall had been retrofitted with an FRP overlay to increase its shear strength. Additional numerical analyses are conducted to further investigate the efficiency of this retrofit scheme for barbell walls with different design characteristics, and to explore the use of textile reinforced mortar (TRM) as an alternative material for the overlay.