diff --git a/_pytest/python.py b/_pytest/python.py
index fa0e7fb02..7611708d4 100644
--- a/_pytest/python.py
+++ b/_pytest/python.py
@@ -266,6 +266,18 @@ class PyobjMixin(PyobjContext):
         return fspath, lineno, modpath
 
 class PyCollector(PyobjMixin, pytest.Collector):
+    def _fixturemapper():
+        def get(self):
+            try:
+                return self._fixturemapper_memo
+            except AttributeError:
+                self._fixturemapper_memo = FixtureMapper(self, funcargs=False)
+                return self._fixturemapper_memo
+        def set(self, val):
+            assert not hasattr(self, "_fixturemapper_memo")
+            self._fixturemapper_memo = val
+        return property(get, set)
+    _fixturemapper = _fixturemapper()
 
     def funcnamefilter(self, name):
         for prefix in self.config.getini("python_functions"):
@@ -309,7 +321,7 @@ class PyCollector(PyobjMixin, pytest.Collector):
         clscol = self.getparent(Class)
         cls = clscol and clscol.obj or None
         transfer_markers(funcobj, cls, module)
-        if not hasattr(self, "_fixturemapper"):
+        if not hasattr(self, "_fixturemapper_memo"):
             self._fixturemapper = FixtureMapper(self)
         fixtureinfo = self._fixturemapper.getfixtureinfo(funcobj, cls)
         metafunc = Metafunc(funcobj, fixtureinfo, self.config,
@@ -331,17 +343,21 @@ class PyCollector(PyobjMixin, pytest.Collector):
                                keywords={callspec.id:True})
 
 class FixtureMapper:
-    def __init__(self, node):
+    def __init__(self, node, funcargs=True):
         self.node = node
         self.fm = node.session._fixturemanager
         self._name2fixtureinfo = {}
+        self.hasfuncargs = funcargs
 
     def getfixtureinfo(self, func, cls):
         try:
             return self._name2fixtureinfo[func]
         except KeyError:
             pass
-        argnames = getfuncargnames(func, int(cls is not None))
+        if self.hasfuncargs:
+            argnames = getfuncargnames(func, int(cls is not None))
+        else:
+            argnames = ()
         usefixtures = getattr(func, "usefixtures", None)
         if usefixtures is not None:
             argnames = usefixtures.args + argnames
@@ -929,17 +945,9 @@ class Function(FunctionMixin, pytest.Item, FuncargnamesCompatAttr):
             for name, val in keywords.items():
                 setattr(self.markers, name, val)
 
-        # contstruct a list of all neccessary fixtures for this test function
-        try:
-            usefixtures = self.markers.usefixtures.args
-        except AttributeError:
-            usefixtures = ()
-        self.fixturenames = (self.session._fixturemanager.getdefaultfixtures() +
-                usefixtures + self._getfuncargnames())
-
-    def _getfuncargnames(self):
-        startindex = int(self.cls is not None)
-        return getfuncargnames(self.obj, startindex=startindex)
+        fixtureinfo = self.parent._fixturemapper.getfixtureinfo(self.obj,
+                                                                self.cls)
+        self.fixturenames = fixtureinfo.names_closure
 
     @property
     def function(self):
diff --git a/_pytest/unittest.py b/_pytest/unittest.py
index 6e19281b4..05c823a6c 100644
--- a/_pytest/unittest.py
+++ b/_pytest/unittest.py
@@ -20,6 +20,7 @@ def pytest_pycollect_makeitem(collector, name, obj):
             return UnitTestCase(name, parent=collector)
 
 class UnitTestCase(pytest.Class):
+
     def collect(self):
         self.session._fixturemanager._parsefactories(self.obj, self.nodeid,
                 unittest=True)
@@ -52,9 +53,6 @@ class UnitTestCase(pytest.Class):
 class TestCaseFunction(pytest.Function):
     _excinfo = None
 
-    def _getfuncargnames(self):
-        return ()
-
     def setup(self):
         self._testcase = self.parent.obj(self.name)
         self._obj = getattr(self._testcase, self.name)
diff --git a/testing/test_python.py b/testing/test_python.py
index 165713474..74ea337a9 100644
--- a/testing/test_python.py
+++ b/testing/test_python.py
@@ -280,6 +280,7 @@ class TestFunction:
         config = testdir.parseconfigure()
         session = testdir.Session(config)
         session._fixturemanager = FixtureManager(session)
+        session._fixturemapper = funcargs.FixtureMapper(session, funcargs=False)
         def func1():
             pass
         def func2():
@@ -579,6 +580,7 @@ class TestFillFixtures:
                 pass
         """)
         funcargs.fillfixtures(item)
+        del item.funcargs["request"]
         assert len(item.funcargs) == 2
         assert item.funcargs['some'] == "test_func"
         assert item.funcargs['other'] == 42
@@ -685,7 +687,9 @@ class TestRequest:
         val2 = req.getfuncargvalue("other")  # see about caching
         assert val2 == 2
         pytest._fillfuncargs(item)
-        assert item.funcargs == {'something': 1}
+        assert item.funcargs["something"] == 1
+        assert len(item.funcargs) == 2
+        assert "request" in item.funcargs
         #assert item.funcargs == {'something': 1, "other": 2}
 
     def test_request_addfinalizer(self, testdir):