diff --git a/gdb/.dir-locals.el b/gdb/.dir-locals.el
index 17df7e327f..a69571a23f 100644
--- a/gdb/.dir-locals.el
+++ b/gdb/.dir-locals.el
@@ -14,6 +14,10 @@
 ;; You should have received a copy of the GNU General Public License
 ;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+;; There are three copies of this file, one in each of gdb/,
+;; gdbserver/, and gdbsupport/.  If you edit any one of these then
+;; please replicate the changes in the other two copies.
+
 (
  (tcl-mode . ((tcl-indent-level . 4)
 	      (tcl-continued-indent-level . 4)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ee0d10d8c9..b3a5e0aa36 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-06  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* .dir-locals.el: Add a comment referencing the other copies of
+	this file.
+
 2020-03-05  John Baldwin  <jhb@FreeBSD.org>
 
 	* fbsd-tdep.c (fbsd_make_corefile_notes): Use std::string for
diff --git a/gdbserver/.dir-locals.el b/gdbserver/.dir-locals.el
new file mode 100644
index 0000000000..a69571a23f
--- /dev/null
+++ b/gdbserver/.dir-locals.el
@@ -0,0 +1,41 @@
+;; Emacs settings.
+;; Copyright (C) 2012-2020 Free Software Foundation, Inc.
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;; There are three copies of this file, one in each of gdb/,
+;; gdbserver/, and gdbsupport/.  If you edit any one of these then
+;; please replicate the changes in the other two copies.
+
+(
+ (tcl-mode . ((tcl-indent-level . 4)
+	      (tcl-continued-indent-level . 4)
+	      (indent-tabs-mode . t)))
+ (nil . ((bug-reference-url-format . "http://sourceware.org/bugzilla/show_bug.cgi?id=%s")))
+ (c-mode . ((c-file-style . "GNU")
+	    (mode . c++)
+	    (indent-tabs-mode . t)
+	    (tab-width . 8)
+	    (c-basic-offset . 2)
+	    (eval . (c-set-offset 'innamespace 0))
+	    ))
+ (c++-mode . ((eval . (when (fboundp 'c-toggle-comment-style)
+			(c-toggle-comment-style 1)))
+	      (indent-tabs-mode . t)
+	      (tab-width . 8)
+	      (c-file-style . "GNU")
+	      (c-basic-offset . 2)
+	      (eval . (c-set-offset 'innamespace 0))
+	      ))
+)
diff --git a/gdbserver/ChangeLog b/gdbserver/ChangeLog
index 4e44a763cc..16346de8de 100644
--- a/gdbserver/ChangeLog
+++ b/gdbserver/ChangeLog
@@ -1,3 +1,7 @@
+2020-03-06  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* .dir-locals.el: New file.
+
 2020-03-05  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>
 
 	* .gitattributes: New file.
diff --git a/gdbsupport/.dir-locals.el b/gdbsupport/.dir-locals.el
new file mode 100644
index 0000000000..a69571a23f
--- /dev/null
+++ b/gdbsupport/.dir-locals.el
@@ -0,0 +1,41 @@
+;; Emacs settings.
+;; Copyright (C) 2012-2020 Free Software Foundation, Inc.
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;; There are three copies of this file, one in each of gdb/,
+;; gdbserver/, and gdbsupport/.  If you edit any one of these then
+;; please replicate the changes in the other two copies.
+
+(
+ (tcl-mode . ((tcl-indent-level . 4)
+	      (tcl-continued-indent-level . 4)
+	      (indent-tabs-mode . t)))
+ (nil . ((bug-reference-url-format . "http://sourceware.org/bugzilla/show_bug.cgi?id=%s")))
+ (c-mode . ((c-file-style . "GNU")
+	    (mode . c++)
+	    (indent-tabs-mode . t)
+	    (tab-width . 8)
+	    (c-basic-offset . 2)
+	    (eval . (c-set-offset 'innamespace 0))
+	    ))
+ (c++-mode . ((eval . (when (fboundp 'c-toggle-comment-style)
+			(c-toggle-comment-style 1)))
+	      (indent-tabs-mode . t)
+	      (tab-width . 8)
+	      (c-file-style . "GNU")
+	      (c-basic-offset . 2)
+	      (eval . (c-set-offset 'innamespace 0))
+	      ))
+)
diff --git a/gdbsupport/ChangeLog b/gdbsupport/ChangeLog
index 6bfd676872..04944a17b4 100644
--- a/gdbsupport/ChangeLog
+++ b/gdbsupport/ChangeLog
@@ -1,3 +1,7 @@
+2020-03-06  Andrew Burgess  <andrew.burgess@embecosm.com>
+
+	* .dir-locals.el: New file.
+
 2020-03-05  Vyacheslav Petrishchev  <vyachemail@gmail.com>
 
 	* configure.ac: Added call development.sh.