Processing-in-DRAM (DRAM-PIM) has emerged as a promising technology for accelerating memory-intensive operations in modern applications, such as Large Language Models (LLMs).Despite its potential, current software stacks for DRAM-PIM face significant challenges, including reliance on hand-tuned libraries that hinder programmability, limited support for high-level abstractions, and the lack of systematic optimization frameworks.To address these limitations, we present ATiM, a search-based optimizing tensor compiler for UPMEM.Key features of ATiM include: (1) automated searches of the joint search space for host and kernel tensor programs, (2) PIM-aware optimizations for efficiently handling boundary conditions, and ( 3) improved search algorithms for the expanded search space of UPMEM systems.Our experimental results on UPMEM hardware demonstrate performance gains of up to 6.18× for various UPMEM benchmark kernels and 8.21× for GPT-J layers.To the best of our knowledge, ATiM is the first tensor compiler to provide fully automated, autotuning-integrated code generation support for a DRAM-PIM system.By bridging the gap between high-level tensor computation abstractions and low-level hardware-specific requirements, ATiM establishes a foundation for advancing DRAM-PIM programmability and enabling streamlined optimization.