“Every couple days, I’m getting calls from manufacturers who want to move their businesses here from China,” said Bradley Gordon, an American lawyer in Phnom Penh.

But multinational companies are finding that they can run from China’s rising wages but cannot truly hide. The populations, economies and even electricity output of most Southeast Asian countries are smaller than in many Chinese provinces, and sometimes smaller than a single Chinese city. As companies shift south, they quickly use up local labor supplies and push wages up sharply.

While wages and benefits often remain below levels needed to provide proper housing and balanced diets, the manufacturing investment — foreign direct investment in Cambodia rose 70 percent last year from 2011 — is starting to raise millions of people out of destitution. “People along the Mekong River are being lifted out of poverty by foreign investment inflows driven by higher Chinese wages,” said Peter Brimble, the senior economist for Cambodia at the Asian Development Bank.

Only a smattering of companies, mostly in low-tech sectors like garment and shoe manufacturing, are seeking to leave China entirely. Many more companies are building new factories in Southeast Asia to supplement operations in China. China’s fast-growing domestic market, large population and huge industrial base still make it attractive for many companies, while productivity in China is rising almost as fast as wages in many industries.

Foreign investment in China nonetheless slipped 3.5 percent last year, after rising every year since 1980 except 1999, during the Asian financial crisis, and 2009, during the global financial crisis. Still, at $119.7 billion, foreign investment in China continues to dwarf investment elsewhere.