diff -r 5fea362b92fc Lib/inspect.py
--- a/Lib/inspect.py	Wed Apr 25 19:45:11 2012 +0200
+++ b/Lib/inspect.py	Wed Apr 25 22:30:46 2012 +0200
@@ -1217,3 +1217,19 @@
     if generator.gi_frame.f_lasti == -1:
         return GEN_CREATED
     return GEN_SUSPENDED
+
+def unwrap(func):
+    """Get the object wrapped by 'func'.
+
+    Follow the chain of __wrapped__ attributes,
+    and return the last object in the chain.
+    If there is a cycle, raise a ValueError.
+    """
+    memo = {id(func)}
+    while hasattr(func, '__wrapped__'):
+        func = func.__wrapped__
+        if id(func) in memo:
+            raise ValueError('wrapper loop')
+        else:
+            memo.add(id(func))
+    return func
diff -r 5fea362b92fc Lib/test/test_inspect.py
--- a/Lib/test/test_inspect.py	Wed Apr 25 19:45:11 2012 +0200
+++ b/Lib/test/test_inspect.py	Wed Apr 25 22:30:46 2012 +0200
@@ -8,6 +8,7 @@
 import collections
 import os
 import shutil
+import functools
 from os.path import normcase
 
 from test.support import run_unittest, TESTFN, DirsOnSysPath
@@ -1170,13 +1171,44 @@
             self.assertIn(name, str(state))
 
 
+class TestUnwrap(unittest.TestCase):
+
+    def test_unwrap(self):
+        def func(a, b):
+            return a + b
+        wrapper = functools.lru_cache(maxsize=20)(func)
+        self.assertIs(inspect.unwrap(wrapper), func)
+
+    def test_cycle(self):
+        def func1(): pass
+        func1.__wrapped__ = func1
+        with self.assertRaisesRegex(ValueError, 'wrapper loop'):
+            inspect.unwrap(func1)
+
+        def func2(): pass
+        func2.__wrapped__ = func1
+        func1.__wrapped__ = func2
+        with self.assertRaisesRegex(ValueError, 'wrapper loop'):
+            inspect.unwrap(func1)
+        with self.assertRaisesRegex(ValueError, 'wrapper loop'):
+            inspect.unwrap(func2)
+
+    def test_unhashable(self):
+        def func(): pass
+        func.__wrapped__ = None
+        class C:
+            __hash__ = None
+            __wrapped__ = func
+        self.assertIs(inspect.unwrap(C()), None)
+
+
 def test_main():
     run_unittest(
         TestDecorators, TestRetrievingSourceCode, TestOneliners, TestBuggyCases,
         TestInterpreterStack, TestClassesAndFunctions, TestPredicates,
         TestGetcallargsFunctions, TestGetcallargsMethods,
         TestGetcallargsUnboundMethods, TestGetattrStatic, TestGetGeneratorState,
-        TestNoEOL
+        TestNoEOL, TestUnwrap
     )
 
 if __name__ == "__main__":