diff --git a/mercurial/changelog.py b/mercurial/changelog.py
--- a/mercurial/changelog.py
+++ b/mercurial/changelog.py
@@ -27,6 +27,8 @@
     stringutil,
 )
 
+from .revlogutils import sidedata as sidedatamod
+
 _defaultextra = {b'branch': b'default'}
 
 
@@ -676,6 +678,7 @@
                     _(b'the name \'%s\' is reserved') % branch
                 )
         sortedfiles = sorted(files)
+        sidedata = None
         if extra is not None:
             for name in (
                 b'p1copies',
@@ -704,13 +707,25 @@
                 extra[b'filesadded'] = filesadded
             if filesremoved is not None:
                 extra[b'filesremoved'] = filesremoved
+        elif self._copiesstorage == b'changeset-sidedata':
+            sidedata = {}
+            if p1copies is not None:
+                sidedata[sidedatamod.SD_P1COPIES] = p1copies
+            if p2copies is not None:
+                sidedata[sidedatamod.SD_P2COPIES] = p2copies
+            if filesadded is not None:
+                sidedata[sidedatamod.SD_FILESADDED] = filesadded
+            if filesremoved is not None:
+                sidedata[sidedatamod.SD_FILESREMOVED] = filesremoved
 
         if extra:
             extra = encodeextra(extra)
             parseddate = b"%s %s" % (parseddate, extra)
         l = [hex(manifest), user, parseddate] + sortedfiles + [b"", desc]
         text = b"\n".join(l)
-        return self.addrevision(text, transaction, len(self), p1, p2)
+        return self.addrevision(
+            text, transaction, len(self), p1, p2, sidedata=sidedata
+        )
 
     def branchinfo(self, rev):
         """return the branch name and open/close state of a revision
diff --git a/mercurial/interfaces/repository.py b/mercurial/interfaces/repository.py
--- a/mercurial/interfaces/repository.py
+++ b/mercurial/interfaces/repository.py
@@ -1547,6 +1547,10 @@
 
     names = interfaceutil.Attribute("""A ``namespaces`` instance.""")
 
+    filecopiesmode = interfaceutil.Attribute(
+        """The way files copies should be dealt with in this repo."""
+    )
+
     def close():
         """Close the handle on this repository."""
 
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -825,10 +825,13 @@
     else:  # explicitly mark repo as using revlogv0
         options[b'revlogv0'] = True
 
-    writecopiesto = ui.config(b'experimental', b'copies.write-to')
-    copiesextramode = (b'changeset-only', b'compatibility')
-    if writecopiesto in copiesextramode:
-        options[b'copies-storage'] = b'extra'
+    if COPIESSDC_REQUIREMENT in requirements:
+        options[b'copies-storage'] = b'changeset-sidedata'
+    else:
+        writecopiesto = ui.config(b'experimental', b'copies.write-to')
+        copiesextramode = (b'changeset-only', b'compatibility')
+        if writecopiesto in copiesextramode:
+            options[b'copies-storage'] = b'extra'
 
     return options
 
@@ -1182,6 +1185,10 @@
 
         self._extrafilterid = repoview.extrafilter(ui)
 
+        self.filecopiesmode = None
+        if COPIESSDC_REQUIREMENT in self.requirements:
+            self.filecopiesmode = b'changeset-sidedata'
+
     def _getvfsward(self, origfunc):
         """build a ward for self.vfs"""
         rref = weakref.ref(self)
@@ -2949,12 +2956,17 @@
         p1, p2 = ctx.p1(), ctx.p2()
         user = ctx.user()
 
-        writecopiesto = self.ui.config(b'experimental', b'copies.write-to')
-        writefilecopymeta = writecopiesto != b'changeset-only'
-        writechangesetcopy = writecopiesto in (
-            b'changeset-only',
-            b'compatibility',
-        )
+        if self.filecopiesmode == b'changeset-sidedata':
+            writechangesetcopy = True
+            writefilecopymeta = True
+            writecopiesto = None
+        else:
+            writecopiesto = self.ui.config(b'experimental', b'copies.write-to')
+            writefilecopymeta = writecopiesto != b'changeset-only'
+            writechangesetcopy = writecopiesto in (
+                b'changeset-only',
+                b'compatibility',
+            )
         p1copies, p2copies = None, None
         if writechangesetcopy:
             p1copies = ctx.p1copies()
diff --git a/mercurial/revlogutils/sidedata.py b/mercurial/revlogutils/sidedata.py
--- a/mercurial/revlogutils/sidedata.py
+++ b/mercurial/revlogutils/sidedata.py
@@ -48,6 +48,12 @@
 SD_TEST6 = 6
 SD_TEST7 = 7
 
+# key to store copies related information
+SD_P1COPIES = 8
+SD_P2COPIES = 9
+SD_FILESADDED = 10
+SD_FILESREMOVED = 11
+
 # internal format constant
 SIDEDATA_HEADER = struct.Struct(r'>H')
 SIDEDATA_ENTRY = struct.Struct(r'>HL20s')
diff --git a/tests/test-copies-in-changeset.t b/tests/test-copies-in-changeset.t
--- a/tests/test-copies-in-changeset.t
+++ b/tests/test-copies-in-changeset.t
@@ -75,7 +75,17 @@
   p1copies: 0\x00a (esc)
   1\x00a (esc)
   2\x00a (esc)
-
+#else
+  $ hg debugsidedata -c -v -- -1
+  4 sidedata entries
+   entry-0010 size 11
+    '0\x00a\n1\x00a\n2\x00a'
+   entry-0011 size 0
+    ''
+   entry-0012 size 5
+    '0\n1\n2'
+   entry-0013 size 0
+    ''
 #endif
 
   $ hg showcopies
@@ -107,6 +117,17 @@
   
   p1copies: 1\x00b (esc)
 
+#else
+  $ hg debugsidedata -c -v -- -1
+  4 sidedata entries
+   entry-0010 size 3
+    '1\x00b'
+   entry-0011 size 0
+    ''
+   entry-0012 size 1
+    '1'
+   entry-0013 size 1
+    '0'
 #endif
 
   $ hg showcopies
@@ -145,6 +166,17 @@
   
   p1copies: 0\x00b2 (esc)
 
+#else
+  $ hg debugsidedata -c -v -- -1
+  4 sidedata entries
+   entry-0010 size 4
+    '0\x00b2'
+   entry-0011 size 0
+    ''
+   entry-0012 size 0
+    ''
+   entry-0013 size 0
+    ''
 #endif
 
   $ hg showcopies
@@ -197,6 +229,17 @@
   2\x00f (esc)
   p2copies: 1\x00d (esc)
 
+#else
+  $ hg debugsidedata -c -v -- -1
+  4 sidedata entries
+   entry-0010 size 7
+    '0\x00a\n2\x00f'
+   entry-0011 size 3
+    '1\x00d'
+   entry-0012 size 5
+    '0\n1\n2'
+   entry-0013 size 0
+    ''
 #endif
 
   $ hg showcopies
@@ -218,6 +261,16 @@
   p2copies: 
 #else
   $ hg ci -m 'copy a to j'
+  $ hg debugsidedata -c -v -- -1
+  4 sidedata entries
+   entry-0010 size 3
+    '0\x00a'
+   entry-0011 size 0
+    ''
+   entry-0012 size 1
+    '0'
+   entry-0013 size 0
+    ''
 #endif
   $ hg debugdata j 0
   \x01 (esc)
@@ -243,6 +296,16 @@
 #else
   $ hg ci --amend -m 'copy a to j, v2'
   saved backup bundle to $TESTTMP/repo/.hg/strip-backup/*-*-amend.hg (glob)
+  $ hg debugsidedata -c -v -- -1
+  4 sidedata entries
+   entry-0010 size 3
+    '0\x00a'
+   entry-0011 size 0
+    ''
+   entry-0012 size 1
+    '0'
+   entry-0013 size 0
+    ''
 #endif
   $ hg showcopies --config experimental.copies.read-from=filelog-only
   a -> j
@@ -260,6 +323,16 @@
   p2copies: 
 #else
   $ hg ci -m 'modify j'
+  $ hg debugsidedata -c -v -- -1
+  4 sidedata entries
+   entry-0010 size 0
+    ''
+   entry-0011 size 0
+    ''
+   entry-0012 size 0
+    ''
+   entry-0013 size 0
+    ''
 #endif
 
 Test writing only to filelog
@@ -273,6 +346,16 @@
   
 #else
   $ hg ci -m 'copy a to k'
+  $ hg debugsidedata -c -v -- -1
+  4 sidedata entries
+   entry-0010 size 3
+    '0\x00a'
+   entry-0011 size 0
+    ''
+   entry-0012 size 1
+    '0'
+   entry-0013 size 0
+    ''
 #endif
 
   $ hg debugdata k 0