diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -637,9 +637,6 @@ coreconfigitem('extdata', '.*',
     default=None,
     generic=True,
 )
-coreconfigitem('format', 'aggressivemergedeltas',
-    default=True,
-)
 coreconfigitem('format', 'chunkcachesize',
     default=None,
 )
@@ -930,6 +927,10 @@ coreconfigitem('progress', 'width',
 coreconfigitem('push', 'pushvars.server',
     default=False,
 )
+coreconfigitem('revlog', 'optimize-delta-parent-choice',
+    default=True,
+    # formely an experimental option: format.aggressivemergedeltas
+)
 coreconfigitem('server', 'bookmarks-pushkey-compat',
     default=True,
 )
diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -1773,6 +1773,20 @@ have a definite end point.
 
 Alias definitions for revsets. See :hg:`help revsets` for details.
 
+``revlog``
+----------
+
+Control the strategy Mercurial uses internally to store history. Options in this
+category impact performance and repository size.
+
+``optimize-delta-parent-choice``
+    When storing a merge revision, both parents will be equally considered as
+    a possible delta base. This results in better delta selection and improved
+    revlog compression. This option is enabled by default.
+
+    Turning this option off can result in large increase of repository size for
+    repository with many merges.
+
 ``server``
 ----------
 
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -668,9 +668,8 @@ class localrepository(object):
         manifestcachesize = self.ui.configint('format', 'manifestcachesize')
         if manifestcachesize is not None:
             self.svfs.options['manifestcachesize'] = manifestcachesize
-        # experimental config: format.aggressivemergedeltas
-        deltabothparents = self.ui.configbool('format',
-                                              'aggressivemergedeltas')
+        deltabothparents = self.ui.configbool('revlog',
+                                              'optimize-delta-parent-choice')
         self.svfs.options['deltabothparents'] = deltabothparents
         self.svfs.options['lazydeltabase'] = not scmutil.gddeltaconfig(self.ui)
         chainspan = self.ui.configbytes('experimental', 'maxdeltachainspan')
diff --git a/tests/test-generaldelta.t b/tests/test-generaldelta.t
--- a/tests/test-generaldelta.t
+++ b/tests/test-generaldelta.t
@@ -118,7 +118,7 @@ delta coming from the server base delta 
         2       1        2        0      p1         57        135        161   1.19259       218        57    0.35404
         3       1        2        0      p1         57        135        161   1.19259       275       114    0.70807
 
-Test format.aggressivemergedeltas
+Test revlog.optimize-delta-parent-choice
 
   $ hg init --config format.generaldelta=1 aggressive
   $ cd aggressive
@@ -146,7 +146,7 @@ Test format.aggressivemergedeltas
 - Verify aggressive merge uses p2 (commit 0) as delta parent
   $ hg up -q -C 1
   $ hg merge -q 0
-  $ hg commit -q -m merge --config format.aggressivemergedeltas=True
+  $ hg commit -q -m merge --config revlog.optimize-delta-parent-choice=yes
   $ hg debugdeltachain -m
       rev  chain# chainlen     prev   delta       size    rawsize  chainsize     ratio   lindist extradist extraratio
         0       1        1       -1    base         59        215         59   0.27442        59         0    0.00000