diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -121,6 +121,8 @@ if os.path.isdir('.hg'):
     env = {'PYTHONPATH': os.pathsep.join(pypath),
            'HGRCPATH': '',
            'LANGUAGE': 'C'}
+    if 'LD_LIBRARY_PATH' in os.environ:
+        env['LD_LIBRARY_PATH'] = os.environ['LD_LIBRARY_PATH']
     if 'SystemRoot' in os.environ:
         # Copy SystemRoot into the custom environment for Python 2.6
         # under Windows. Otherwise, the subprocess will fail with