diff --git a/Doc/Manual/Python.html b/Doc/Manual/Python.html
index e766baaf0..0c88185cb 100644
--- a/Doc/Manual/Python.html
+++ b/Doc/Manual/Python.html
@@ -2350,14 +2350,71 @@ please refer to the python documentation:</p>
 
 <p>Use of the <tt>-builtin</tt> option implies a couple of limitations:
 <ul>
-<li>Some legacy syntax is no longer supported; in particular:</li>
+<li><p>Some legacy syntax is no longer supported; in particular:</p></li>
 <ul>
 <li>The functional interface is no longer exposed.  For example, you may no longer call <tt>Whizzo.new_CrunchyFrog()</tt>.  Instead, you must use <tt>Whizzo.CrunchyFrog()</tt>.</li>
 <li>Static member variables are no longer accessed through the 'cvar' field (e.g., <tt>Dances.cvar.FishSlap</tt>).
 They are instead accessed in the idiomatic way (<tt>Dances.FishSlap</tt>).</li>
 </ul>
-<li>Wrapped types may not be thrown as python exceptions</li>
-<li>Reverse operators are not supported.</li>
+<li><p>Wrapped types may not be thrown as python exceptions.  Here's why: the python internals expect that all sub-classes of Exception will have this struct layout:</p>
+
+<div class="code">
+<pre>
+typedef struct {
+    PyObject_HEAD
+    PyObject *dict;
+    PyObject *args;
+    PyObject *message;
+} PyBaseExceptionObject;
+</pre>
+</div>
+
+<p>But swig-generated wrappers expect that all swig-wrapped classes will have this struct layout:</p>
+
+<div class="code">
+<pre>
+typedef struct {
+    PyObject_HEAD
+    void *ptr;
+    swig_type_info *ty;
+    int own;
+    PyObject *next;
+    PyObject *dict;
+} SwigPyObject;
+</pre>
+</div>
+
+<p>There are workarounds for this.  For example, if you wrap this class:
+
+<div class="code">
+<pre>
+class MyException {
+public:
+    MyException (const char *msg_);
+    ~MyException ();
+
+    const char *what () const;
+
+private:
+    char *msg;
+};
+</pre>
+</div>
+
+<p>... you can define this python class, which may be raised as an exception:</p>
+
+<div class="targetlang">
+<pre>
+class MyPyException (Exception, MyException) :
+    def __init__(self, msg, *args) :
+        Exception.__init__(self, *args)
+        self.myexc = MyException(msg)
+    def what (self) :
+        return self.myexc.what()
+</pre>
+</div>
+</li>
+<li><p>Reverse binary operators (e.g., <tt>__radd__</tt>) are not supported.</p></li>
 </ul>
 </p>
 
diff --git a/Lib/python/builtin.swg b/Lib/python/builtin.swg
index ffd3fbd1c..876bcd1cc 100644
--- a/Lib/python/builtin.swg
+++ b/Lib/python/builtin.swg
@@ -409,3 +409,13 @@ SwigPyBuiltin_ThisClosure (PyObject *self, void *closure) {
   Py_XINCREF(result);
   return result;
 }
+
+SWIGINTERN void
+SwigPyBuiltin_SetMetaType (PyTypeObject *type, PyTypeObject *metatype)
+{
+#if PY_VERSION_HEX >= 0x03000000
+    type->ob_base.ob_base.ob_type = metatype;
+#else
+    type->ob_type = metatype;
+#endif
+}
diff --git a/Lib/python/pyinit.swg b/Lib/python/pyinit.swg
index 88d2d3f16..088eb0ab0 100644
--- a/Lib/python/pyinit.swg
+++ b/Lib/python/pyinit.swg
@@ -355,9 +355,6 @@ SWIG_init(void) {
   Py_DECREF(metatype_args);
   metatype->tp_setattro = (setattrofunc) &SwigPyObjectType_setattro;
   assert(PyType_Ready(metatype) >= 0);
-
-  SWIG_Python_builtin_imports();
-
 #endif
 
   /* Fix SwigMethods to carry the callback ptrs when needed */
diff --git a/Source/Modules/python.cxx b/Source/Modules/python.cxx
index 0b6f968e1..fe63a3dbc 100644
--- a/Source/Modules/python.cxx
+++ b/Source/Modules/python.cxx
@@ -44,8 +44,8 @@ static File *f_directors_h = 0;
 static File *f_init = 0;
 static File *f_shadow_py = 0;
 static String *f_shadow = 0;
-static String *f_shadow_imports = 0;
-static String *f_shadow_import_stmts = 0;
+static Hash *f_shadow_imports = 0;
+static String *f_shadow_builtin_imports = 0;
 static String *f_shadow_stubs = 0;
 static Hash *builtin_getset = 0;
 static Hash *class_members = 0;
@@ -782,24 +782,13 @@ public:
       filen = NULL;
 
       f_shadow = NewString("");
-      f_shadow_imports = NewString("");
-      f_shadow_import_stmts = NewString("");
+      f_shadow_imports = NewHash();
+      f_shadow_builtin_imports = NewString("");
       f_shadow_stubs = NewString("");
 
-      Printv(f_shadow_import_stmts, "SWIGINTERN void\n", NIL);
-      Printv(f_shadow_import_stmts, "SWIG_Python_builtin_imports()\n", NIL);
-      Printv(f_shadow_import_stmts, "{\n", NIL);
-      Printv(f_shadow_import_stmts, tab4 "PyObject *import_str = NULL;\n", NIL);
-
       Swig_register_filebyname("shadow", f_shadow);
       Swig_register_filebyname("python", f_shadow);
 
-      Swig_banner_target_lang(f_shadow, "#");
-
-      if (!modern) {
-	Printv(f_shadow, "# This file is compatible with both classic and new-style classes.\n", NIL);
-      }
-
       if (mod_docstring && Len(mod_docstring)) {
 	Printv(f_shadow, "\"\"\"\n", mod_docstring, "\n\"\"\"\n\n", NIL);
 	Delete(mod_docstring);
@@ -982,13 +971,13 @@ public:
     Printf(f_init, "}\n");
 
     if (shadow) {
-      if (builtin) {
-	Printv(f_shadow_import_stmts, "}\n", NIL);
-	Printv(f_header, f_shadow_import_stmts, NIL);
+      Swig_banner_target_lang(f_shadow_py, "#");
+      if (!modern) {
+	Printv(f_shadow, "# This file is compatible with both classic and new-style classes.\n", NIL);
       }
+      Printv(f_shadow_py, "\n", f_shadow_builtin_imports, "\n", NIL);
       Printv(f_shadow_py, f_shadow, "\n", NIL);
       Printv(f_shadow_py, f_shadow_stubs, "\n", NIL);
-
       Close(f_shadow_py);
       Delete(f_shadow_py);
     }
@@ -1066,25 +1055,13 @@ public:
 	if (shadowimport) {
 	  if (!options || (!Getattr(options, "noshadow") && !Getattr(options, "noproxy"))) {
 	    Printf(import, "_%s\n", modname);
-	    if (!Strstr(f_shadow_imports, import)) {
+	    if (!GetFlagAttr(f_shadow_imports, import)) {
 	      if (pkg && (!package || Strcmp(pkg, package) != 0)) {
-		if (builtin) {
-		  Printf(f_shadow_import_stmts, tab4 "import_str = PyString_FromString(\"%s.%s\");\n", pkg, modname);
-		  Printf(f_shadow_import_stmts, tab4 "PyImport_Import(import_str);\n");
-		  Printf(f_shadow_import_stmts, tab4 "Py_XDECREF(import_str);\n");
-		} else {
-		  Printf(f_shadow, "import %s.%s\n", pkg, modname);
-		}
+		Printf(builtin ? f_shadow_builtin_imports : f_shadow, "import %s.%s\n", pkg, modname);
 	      } else {
-		if (builtin) {
-		  Printf(f_shadow_import_stmts, tab4 "import_str = PyString_FromString(\"%s\");\n", modname);
-		  Printf(f_shadow_import_stmts, tab4 "PyImport_Import(import_str);\n");
-		  Printf(f_shadow_import_stmts, tab4 "Py_XDECREF(import_str);\n");
-		} else {
-		  Printf(f_shadow, "import %s\n", modname);
-		}
+		Printf(builtin ? f_shadow_builtin_imports : f_shadow, "import %s\n", modname);
 	      }
-	      Printv(f_shadow_imports, import, NULL);
+	      SetFlag(f_shadow_imports, import);
 	    }
 	  }
 	}
@@ -3227,11 +3204,7 @@ public:
     String *templ = NewStringf("SwigPyBuiltin_%s", mname);
     int funpack = modernargs && fastunpack;
 
-    Printv(f_init, "#if PY_VERSION_HEX >= 0x03000000\n", NIL);
-    Printf(f_init, "  builtin_pytype->ob_base.ob_base.ob_type = metatype;\n");
-    Printv(f_init, "#else\n", NIL);
-    Printf(f_init, "  builtin_pytype->ob_type = metatype;\n");
-    Printv(f_init, "#endif\n", NIL);
+    Printv(f_init, "  SwigPyBuiltin_SetMetaType(builtin_pytype, metatype);\n", NIL);
     Printf(f_init, "  builtin_pytype->tp_new = PyType_GenericNew;\n");
     Printv(f_init, "  builtin_base_count = 0;\n", NIL);
     List *baselist = Getattr(n, "bases");
@@ -3848,9 +3821,6 @@ public:
     }
 
     if (builtin) {
-      //Dump(f_shadow, f_builtins);
-      //Printf(f_builtins, "    {NULL} // Sentinel\n};\n\n");
-      //Dump(builtin_methods, f_builtins);
       Clear(class_members);
       Clear(builtin_getset);
       Clear(builtin_methods);