System Prompt Optimization with Meta-Learning
Authors: name: Yumin Choi; name: Jinheon Baek; name: Sung Ju Hwang
Published: 2025-05-14 16:46:15

Abstract: Large Language Models (LLMs) have shown remarkable capabilities, with
optimizing their input prompts playing a pivotal role in maximizing their
performance. However, while LLM prompts consist of both the task-agnostic
system prompts and task-specific user prompts, existing work on prompt
optimization has focused on user prompts specific to individual queries or
tasks, and largely overlooked the system prompt that is, once optimized,
applicable across different tasks and domains. Motivated by this, we introduce
the novel problem of bilevel system prompt optimization, whose objective is to
design system prompts that are robust to diverse user prompts and transferable
to unseen tasks. To tackle this problem, we then propose a meta-learning
framework, which meta-learns the system prompt by optimizing it over various
user prompts across multiple datasets, while simultaneously updating the user
prompts in an iterative manner to ensure synergy between them. We conduct
experiments on 14 unseen datasets spanning 5 different domains, on which we
show that our approach produces system prompts that generalize effectively to
diverse user prompts. Also, our findings reveal that the optimized system
prompt enables rapid adaptation even to unseen tasks, requiring fewer
optimization steps for test-time user prompts while achieving improved
performance.