Do variations in labor market institutions across countries affect the cross-border organization of the firm? Using firm-level data on multinationals located in France, we show that multinational firms are more likely to import intermediate inputs from external independent suppliers instead of importing from their own subsidiaries when importing from countries with empowered unions. Moreover, this effect is stronger for firms operating in capital-intensive industries. We propose a theoretical mechanism that rationalizes these findings. The fragmentation of the value chain weakens the union’s bargaining position, by limiting the amount of revenues that are subject to union extraction. The outsourcing strategy reduces the share of surplus that is appropriated by the union, which enhances the firm’s incentives to invest. Since investment creates relatively more value in capital-intensive industries, increases in union power are more likely to be conducive to outsourcing in those industries. Overall, our findings suggest that multinational firms use their organizational structure strategically when sourcing intermediate inputs from unionized markets.