Index: Lib/xml/dom/expatbuilder.py
===================================================================
--- Lib/xml/dom/expatbuilder.py	(revision 54643)
+++ Lib/xml/dom/expatbuilder.py	(working copy)
@@ -171,9 +171,23 @@
         self._elem_info = self.document._elem_info
         self._cdata = False
 
+    def unlink(self):
+        """Clean up cycles."""
+        if self.document:
+            self.document.unlink()
+            self.document = None
+        self._parser = None
+        self._intern_setdefault = None
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, type, value, traceback):
+        self.unlink()
+
     def install(self, parser):
         """Install the callbacks needed to build the DOM into the parser."""
-        # This creates circular references!
+        # This creates circular references!  Call unlink() to clear them.
         parser.StartDoctypeDeclHandler = self.start_doctype_decl_handler
         parser.StartElementHandler = self.first_element_handler
         parser.EndElementHandler = self.end_element_handler
@@ -211,6 +225,10 @@
             parser.Parse("", True)
         except ParseEscape:
             pass
+        except:
+            self.document.unlink()
+            self.reset()
+            raise
         doc = self.document
         self.reset()
         self._parser = None
@@ -224,6 +242,10 @@
             self._setup_subset(string)
         except ParseEscape:
             pass
+        except:
+            self.document.unlink()
+            self.reset()
+            raise
         doc = self.document
         self.reset()
         self._parser = None
@@ -918,14 +940,12 @@
     else:
         builder = ExpatBuilder()
 
-    if isinstance(file, StringTypes):
-        fp = open(file, 'rb')
-        try:
-            result = builder.parseFile(fp)
-        finally:
-            fp.close()
-    else:
-        result = builder.parseFile(file)
+    with builder:
+        if isinstance(file, StringTypes):
+            with open(file, 'rb') as fp:
+                result = builder.parseFile(fp)
+        else:
+            result = builder.parseFile(file)
     return result
 
 
@@ -937,8 +957,9 @@
         builder = ExpatBuilderNS()
     else:
         builder = ExpatBuilder()
-    return builder.parseString(string)
 
+    with builder:
+        return builder.parseString(string)
 
 def parseFragment(file, context, namespaces=True):
     """Parse a fragment of a document, given the context from which it
@@ -952,14 +973,12 @@
     else:
         builder = FragmentBuilder(context)
 
-    if isinstance(file, StringTypes):
-        fp = open(file, 'rb')
-        try:
-            result = builder.parseFile(fp)
-        finally:
-            fp.close()
-    else:
-        result = builder.parseFile(file)
+    with builder:
+        if isinstance(file, StringTypes):
+            with open(file, 'rb') as fp:
+                result = builder.parseFile(fp)
+        else:
+            result = builder.parseFile(file)
     return result
 
 
@@ -972,8 +991,9 @@
         builder = FragmentBuilderNS(context)
     else:
         builder = FragmentBuilder(context)
-    return builder.parseString(string)
 
+    with builder:
+        return builder.parseString(string)
 
 def makeBuilder(options):
     """Create a builder based on an Options object."""