diff --git a/test/runtests.py b/test/runtests.py
index 86d6122..b65a38e 100644
--- a/test/runtests.py
+++ b/test/runtests.py
@@ -17,6 +17,9 @@ def getoptionparser():
     parser.add_option("-e", "--exclude", type="string",
                       action="append", dest="exclude", default=[],
                       help="exclude tests matching PATTERN", metavar="PATTERN")
+    parser.add_option("--no-builddir",
+                      action="store_false", dest="builddir", default=True,
+                      help="disable testing from build directory")
     parser.add_option("--path", type="string",
                       action="append", dest="path", default=[],
                       help="prepend PATH to sys.path", metavar="PATH")
@@ -56,7 +59,7 @@ def getbuilddir():
 def setup_python(options):
     rootdir = os.path.dirname(os.path.dirname(__file__))
     builddir = os.path.join(rootdir, getbuilddir())
-    if os.path.exists(builddir):
+    if options.builddir and os.path.exists(builddir):
         sys.path.insert(0, builddir)
     if options.path:
         path = options.path[:]
diff --git a/tox.ini b/tox.ini
index b00b51c..eff59ce 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,5 +16,4 @@ envlist =
 [testenv]
 deps =
 commands =
-    {envpython} setup.py -q clean --all
-    {envpython} {toxinidir}/test/runtests.py -q
+    {envpython} {toxinidir}/test/runtests.py --quiet --no-builddir []