This paper presents LRU-SP, a size-adjusted and popularity-aware extension to Least Recently Used (LRU) for caching web objects. The standard LRU, focusing on recently used and equal sized objects, is not suitable for the web context because web objects vary dramatically in size and the recently accessed objects may possibly differ from popular ones. LRU-SP is built on two LRU extensions, namely Size-Adjusted LRU and Segmented LRU. As LRU-SP differentiates object size and access frequency, it can achieve higher hit rates and byte hit rates. Furthermore, an efficient implementation scheme is developed and trace-driven simulations are performed to compare LRU-SP against Size-Adjusted LRU, Segmented LRU and LRV caching algorithms.