MTA: A Merge-then-Adapt Framework for Personalized Large Language Model

Fuente: arXiv
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Main Authors: Li, Xiaopeng, Zheng, Yuanjin, Wang, Wanyu, zhang, wenlin, Jia, Pengyue, Wang, Yiqi, Wang, Maolin, Wei, Xuetao, Zhao, Xiangyu
Format: Preprint
Published: 2025
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author Li, Xiaopeng
Zheng, Yuanjin
Wang, Wanyu
zhang, wenlin
Jia, Pengyue
Wang, Yiqi
Wang, Maolin
Wei, Xuetao
Zhao, Xiangyu
author_facet Li, Xiaopeng
Zheng, Yuanjin
Wang, Wanyu
zhang, wenlin
Jia, Pengyue
Wang, Yiqi
Wang, Maolin
Wei, Xuetao
Zhao, Xiangyu
contents Personalized Large Language Models (PLLMs) aim to align model outputs with individual user preferences, a crucial capability for user-centric applications. However, the prevalent approach of fine-tuning a separate module for each user faces two major limitations: (1) storage costs scale linearly with the number of users, rendering the method unscalable; and (2) fine-tuning a static model from scratch often yields suboptimal performance for users with sparse data. To address these challenges, we propose MTA, a Merge-then-Adapt framework for PLLMs. MTA comprises three key stages. First, we construct a shared Meta-LoRA Bank by selecting anchor users and pre-training meta-personalization traits within meta-LoRA modules. Second, to ensure scalability and enable dynamic personalization combination beyond static models, we introduce an Adaptive LoRA Fusion stage. This stage retrieves and dynamically merges the most relevant anchor meta-LoRAs to synthesize a user-specific one, thereby eliminating the need for user-specific storage and supporting more flexible personalization. Third, we propose a LoRA Stacking for Few-Shot Personalization stage, which applies an additional ultra-low-rank, lightweight LoRA module on top of the merged LoRA. Fine-tuning this module enables effective personalization under few-shot settings. Extensive experiments on the LaMP benchmark demonstrate that our approach outperforms existing SOTA methods across multiple tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2511_20072
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MTA: A Merge-then-Adapt Framework for Personalized Large Language Model
Li, Xiaopeng
Zheng, Yuanjin
Wang, Wanyu
zhang, wenlin
Jia, Pengyue
Wang, Yiqi
Wang, Maolin
Wei, Xuetao
Zhao, Xiangyu
Computation and Language
Personalized Large Language Models (PLLMs) aim to align model outputs with individual user preferences, a crucial capability for user-centric applications. However, the prevalent approach of fine-tuning a separate module for each user faces two major limitations: (1) storage costs scale linearly with the number of users, rendering the method unscalable; and (2) fine-tuning a static model from scratch often yields suboptimal performance for users with sparse data. To address these challenges, we propose MTA, a Merge-then-Adapt framework for PLLMs. MTA comprises three key stages. First, we construct a shared Meta-LoRA Bank by selecting anchor users and pre-training meta-personalization traits within meta-LoRA modules. Second, to ensure scalability and enable dynamic personalization combination beyond static models, we introduce an Adaptive LoRA Fusion stage. This stage retrieves and dynamically merges the most relevant anchor meta-LoRAs to synthesize a user-specific one, thereby eliminating the need for user-specific storage and supporting more flexible personalization. Third, we propose a LoRA Stacking for Few-Shot Personalization stage, which applies an additional ultra-low-rank, lightweight LoRA module on top of the merged LoRA. Fine-tuning this module enables effective personalization under few-shot settings. Extensive experiments on the LaMP benchmark demonstrate that our approach outperforms existing SOTA methods across multiple tasks.
title MTA: A Merge-then-Adapt Framework for Personalized Large Language Model
topic Computation and Language
url https://arxiv.org/abs/2511.20072