Star banking analyst Meredith Whitney upgraded Goldman Sachs (NYSE: GS) from “neutral” to “buy,” saying she expects second-quarter earnings to be $4.65 per share compared with the average analyst estimate of $3.65.

Goldman is scheduled to report earnings tomorrow before the market opens.

Whitney, a former Oppenheimer analyst, operates her own independent consulting firm and covers seven other banks; Goldman is the only bank she rates a “buy”. This is the first time she recommends buying Goldman Sachs since January 2008. Since downgrading Goldman on Feb. 4, 2008, the shares have fallen -25.5%.

Whitney gained national attention when her bearish outlook on the financial sector proved prescient as many of the nation’s banks and brokerages either failed or teetered on the brink of extinction in what became the worst financial crisis since the Great Depression.

Whitney raised her full-year earnings estimates for Goldman, to $19.65, as well as her 2011 estimate, to $22.10. Both exceed most analysts’ expectations. If Whitney is accurate, Goldman will post its largest profit since 2007, when its previous quarterly earnings record of $3.2 billion.

Goldman’s shares — according to Whitney’s rosy outlook — are cheap from an earnings perspective. She expects them to hit $186 within 12 months, a +24.4% gain from their current $149.44.