Jim Cramer has a bold message for portfolio managers looking for growth in a volatile market: sell everything and buy soon-to-be-public Alibaba.

The massive online Chinese retailer, in which Yahoo owns a big stake, could boost the tech company's share price up to $45—a more than 20 percent spike—Cramer said on CNBC's "Squawk on the Street." Yahoo saw shares soar Wednesday morning more than 7 percent after a better-than-expected earnings report that also gave Wall Street a glimpse into Alibaba's massive growth potential.