diff --git a/CMakeLists.txt b/CMakeLists.txt
index bb70f158800..b313780a41f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -250,7 +250,8 @@ set(TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}")
 
 include(HandleLLVMOptions)
 
-# Verify that we can find a Python interpreter,
+# Verify that we can find a Python 2 interpreter.  Python 3 is unsupported.
+set(Python_ADDITIONAL_VERSIONS 2.7 2.6 2.5 2.4)
 include(FindPythonInterp)
 if( NOT PYTHONINTERP_FOUND )
   message(FATAL_ERROR