diff --git a/IPython/config/application.py b/IPython/config/application.py
index 3b848c3..bde3200 100644
--- a/IPython/config/application.py
+++ b/IPython/config/application.py
@@ -118,6 +118,9 @@ class Application(SingletonConfigurable):
     option_description = Unicode(option_description)
     keyvalue_description = Unicode(keyvalue_description)
     subcommand_description = Unicode(subcommand_description)
+    
+    python_config_loader_class = PyFileConfigLoader
+    json_config_loader_class = JSONFileConfigLoader
 
     # The usage and example string that goes at the end of the help string.
     examples = Unicode()
@@ -507,8 +510,8 @@ class Application(SingletonConfigurable):
             path = [path]
         for path in path[::-1]:
             # path list is in descending priority order, so load files backwards:
-            pyloader = PyFileConfigLoader(basefilename+'.py', path=path, log=log)
-            jsonloader = JSONFileConfigLoader(basefilename+'.json', path=path, log=log)
+            pyloader = cls.python_config_loader_class(basefilename+'.py', path=path, log=log)
+            jsonloader = cls.json_config_loader_class(basefilename+'.json', path=path, log=log)
             config = None
             for loader in [pyloader, jsonloader]:
                 try:
diff --git a/IPython/config/loader.py b/IPython/config/loader.py
index e57cc7e..fdd193f 100644
--- a/IPython/config/loader.py
+++ b/IPython/config/loader.py
@@ -436,52 +436,29 @@ class PyFileConfigLoader(FileConfigLoader):
             raise ConfigFileNotFound(str(e))
         self._read_file_as_dict()
         return self.config
-
-
+    
+    def load_subconfig(self, fname, path=None):
+        """Injected into config file namespace as load_subconfig"""
+        if path is None:
+            path = self.path
+        
+        loader = self.__class__(fname, path)
+        try:
+            sub_config = loader.load_config()
+        except ConfigFileNotFound:
+            # Pass silently if the sub config is not there,
+            # treat it as an empty config file.
+            pass
+        else:
+            self.config.merge(sub_config)
+    
     def _read_file_as_dict(self):
         """Load the config file into self.config, with recursive loading."""
-        # This closure is made available in the namespace that is used
-        # to exec the config file.  It allows users to call
-        # load_subconfig('myconfig.py') to load config files recursively.
-        # It needs to be a closure because it has references to self.path
-        # and self.config.  The sub-config is loaded with the same path
-        # as the parent, but it uses an empty config which is then merged
-        # with the parents.
-
-        # If a profile is specified, the config file will be loaded
-        # from that profile
-
-        def load_subconfig(fname, profile=None):
-            # import here to prevent circular imports
-            from IPython.core.profiledir import ProfileDir, ProfileDirError
-            if profile is not None:
-                try:
-                    profile_dir = ProfileDir.find_profile_dir_by_name(
-                            get_ipython_dir(),
-                            profile,
-                    )
-                except ProfileDirError:
-                    return
-                path = profile_dir.location
-            else:
-                path = self.path
-            loader = PyFileConfigLoader(fname, path)
-            try:
-                sub_config = loader.load_config()
-            except ConfigFileNotFound:
-                # Pass silently if the sub config is not there. This happens
-                # when a user s using a profile, but not the default config.
-                pass
-            else:
-                self.config.merge(sub_config)
-
-        # Again, this needs to be a closure and should be used in config
-        # files to get the config being loaded.
         def get_config():
             return self.config
-
+        
         namespace = dict(
-            load_subconfig=load_subconfig,
+            load_subconfig=self.load_subconfig,
             get_config=get_config,
             __file__=self.full_filename,
         )
diff --git a/IPython/core/application.py b/IPython/core/application.py
index 9741baa..87999d7 100644
--- a/IPython/core/application.py
+++ b/IPython/core/application.py
@@ -20,7 +20,7 @@ import shutil
 import sys
 
 from IPython.config.application import Application, catch_config_error
-from IPython.config.loader import ConfigFileNotFound
+from IPython.config.loader import ConfigFileNotFound, PyFileConfigLoader
 from IPython.core import release, crashhandler
 from IPython.core.profiledir import ProfileDir, ProfileDirError
 from IPython.utils.path import get_ipython_dir, get_ipython_package_dir, ensure_dir_exists
@@ -63,6 +63,19 @@ base_flags = dict(
             """)
 )
 
+class ProfileAwareConfigLoader(PyFileConfigLoader):
+    """A Python file config loader that is aware of IPython profiles."""
+    def load_subconfig(self, fname, path=None, profile=None):
+        if profile is not None:
+            try:
+                profile_dir = ProfileDir.find_profile_dir_by_name(
+                        get_ipython_dir(),
+                        profile,
+                )
+            except ProfileDirError:
+                return
+            path = profile_dir.location
+        return super(ProfileAwareConfigLoader, self).load_subconfig(fname, path=path)
 
 class BaseIPythonApplication(Application):
 
@@ -73,6 +86,9 @@ class BaseIPythonApplication(Application):
     aliases = Dict(base_aliases)
     flags = Dict(base_flags)
     classes = List([ProfileDir])
+    
+    # enable `load_subconfig('cfg.py', profile='name')`
+    python_config_loader_class = ProfileAwareConfigLoader
 
     # Track whether the config_file has changed,
     # because some logic happens only if we aren't using the default.