Social Security benefits are a great source of supplemental income for seniors in retirement. But since Social Security generally provides the average retiree with only 40% of his or her pre-retirement income, the vast majority of retirees need to build up investment nest eggs to help pay for expenses that Social Security benefits alone won't cover.

The auto parts retailer AutoZone (AZO -0.59%) and home products retailer Williams-Sonoma (WSM -0.19%) are stocks that can help investors build up that wealth ahead of retirement. They also happen to be trading at a discount currently. Let's find out if these two cheap stocks might be able to help fund someone's retirement.

1. AutoZone

When owners have issues with their vehicles, they have two main options to get them back up and running. Either they diagnose and resolve the issue themselves if they have the appropriate knowledge, or they take them to a repair shop and have the issue corrected.

Regardless of which option is chosen, there's a good chance that the replacement parts for the repair will come from one of AutoZone's almost 7,000 stores. With locations scattered across the U.S., Mexico, and Brazil, there's a store within a reasonable distance of most drivers in these countries.

As long as there are vehicles on the road, the market for replacement auto parts will be there. This bodes well for AutoZone's long-term sustainability as a company. In the near term, AutoZone benefits from a U.S. vehicle fleet with an average age that exceeds 12 years. Older cars require more frequent and costly repairs, which is why analysts forecast that AutoZone will deliver 13.3% annual diluted earnings per share (EPS) growth over the next five years.

For context, AutoZone delivered 19.2% annual total returns over the last 10 years. This turned a $10,000 investment into $58,000 during that time, which was nearly double the $31,000 that a $10,000 investment in the S&P 500 index matured into during that period. 

Simply assuming that AutoZone's valuation multiple remains unchanged, the company should have no problem delivering low-teens percentage annual total returns over the next five- to 10 years. While the market in the U.S. is relatively mature, a growing store count in Mexico and Brazil should be a growth catalyst for the company. Less than 800 of the company's stores are in these two markets, which is a relatively low store count for the two highly populated countries.

At first glance, the company's forward price-to-earnings (P/E) ratio of 15.4 may not seem cheap compared to the industry average forward P/E ratio of 13.4. But AutoZone's annual earnings growth outlook is far above the medium-term industry growth outlook of 9.9% each year. This arguably justifies AutoZone's higher valuation.

A person works on their finances.

Image source: Getty Images.

2. Williams-Sonoma

The management team of the home goods retailer Williams-Sonoma must have a crystal ball, because they saw the future long before most other retailers. The future I'm referring to is omnichannel retail. Omnichannel retail is simply a balanced approach between brick-and-mortar stores and e-commerce to provide the most all-encompassing customer service possible. In other words, the company is basically the blueprint of how to not only survive, but to thrive in the current retail environment.

For customers seeking an in-person shopping experience, Williams-Sonoma has nearly 550 stores that contribute to approximately one-third of its total net sales. And if customers are prioritizing convenience, the company's well-established e-commerce platform is also a great choice that makes up the other two-thirds of total net sales.

Williams-Sonoma's savvy management and strong brand recognition via its eponymous Williams-Sonoma, West Elm, and Pottery Barn brands are why analysts are anticipating 5% annual earnings growth through the next five years. Given that these projections are modeling in a recession and housing downturn, resulting in less home goods spending in the near future, this would be a solid growth rate.

Williams-Sonoma has outperformed the S&P 500 index over the last 10 years, parlaying a $10,000 investment from 10 years ago into nearly $35,000 with dividends reinvested. Similarly, strong returns could continue in the years ahead because of two large and mostly untapped market opportunities for the company: The $450 billion global home category and the $80 billion business-to-business category. Using its similar omnichannel strategy in these markets and duplicating its 3% U.S. market share, over time, Williams-Sonoma could triple its total revenue.

And for a measly forward P/E ratio of 7.7, investors can buy Williams-Sonoma's 2.6% dividend yield on the cheap. This is considerably below the apparel, accessories, and luxury goods industry average forward P/E ratio of 10, which makes the stock a compelling pick for investors.