diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -1338,6 +1338,12 @@
     generic=True,
 )
 coreconfigitem(
+    b'hooks',
+    b'.*:run-with-plain',
+    default=True,
+    generic=True,
+)
+coreconfigitem(
     b'hgweb-paths',
     b'.*',
     default=list,
diff --git a/mercurial/helptext/config.txt b/mercurial/helptext/config.txt
--- a/mercurial/helptext/config.txt
+++ b/mercurial/helptext/config.txt
@@ -1027,6 +1027,11 @@
   incoming.autobuild = /my/build/hook
   # force autobuild hook to run before other incoming hooks
   priority.incoming.autobuild = 1
+  ###  control HGPLAIN setting when running autobuild hook
+  # HGPLAIN always set (default from Mercurial 5.7)
+  incoming.autobuild:run-with-plain = yes
+  # HGPLAIN never set
+  incoming.autobuild:run-with-plain = no
 
 Most hooks are run with environment variables set that give useful
 additional information. For each hook below, the environment variables
diff --git a/mercurial/hook.py b/mercurial/hook.py
--- a/mercurial/hook.py
+++ b/mercurial/hook.py
@@ -157,7 +157,12 @@
             env[b'HG_PENDING'] = repo.root
     env[b'HG_HOOKTYPE'] = htype
     env[b'HG_HOOKNAME'] = name
-    env[b'HGPLAIN'] = b'1'
+
+    plain = ui.configbool(b'hooks', b'%s:run-with-plain' % name)
+    if plain:
+        env[b'HGPLAIN'] = b'1'
+    else:
+        env[b'HGPLAIN'] = b''
 
     for k, v in pycompat.iteritems(args):
         # transaction changes can accumulate MBs of data, so skip it
diff --git a/tests/test-hook.t b/tests/test-hook.t
--- a/tests/test-hook.t
+++ b/tests/test-hook.t
@@ -1407,13 +1407,21 @@
 
   $ cat << EOF >> .hg/hgrc
   > [hooks]
-  > pre-version.testing-default=echo '### default ###' plain: \$HGPLAIN
+  > pre-version.testing-default=echo '### default ###' plain: \${HGPLAIN:-'<unset>'}
+  > pre-version.testing-yes=echo '### yes #######' plain: \${HGPLAIN:-'<unset>'}
+  > pre-version.testing-yes:run-with-plain=yes
+  > pre-version.testing-no=echo '### no ########' plain: \${HGPLAIN:-'<unset>'}
+  > pre-version.testing-no:run-with-plain=no
   > EOF
 
   $ (unset HGPLAIN; hg version --quiet)
   ### default ### plain: 1
+  ### yes ####### plain: 1
+  ### no ######## plain: <unset>
   Mercurial Distributed SCM (*) (glob)
 
   $ HGPLAIN=1 hg version --quiet
   ### default ### plain: 1
+  ### yes ####### plain: 1
+  ### no ######## plain: <unset>
   Mercurial Distributed SCM (*) (glob)