diff --git a/doc/hgrc.5.txt b/doc/hgrc.5.txt
--- a/doc/hgrc.5.txt
+++ b/doc/hgrc.5.txt
@@ -910,6 +910,16 @@ User interface controls.
     The conflict resolution program to use during a manual merge.
     For more information on merge tools see :hg:`help merge-tools`.
     For configuring merge tools see the merge-tools_ section.
+``portablefilenames``
+    Check for portable filenames. Can be ``warn``, ``ignore`` or ``abort``.
+    Default is ``warn``.
+    If set to ``warn`` (or ``true``), a warning message is printed on POSIX
+    platforms, if a file with a non-portable filename is added (e.g. a file
+    with a name that can't be created on Windows because it contains reserved
+    parts like ``AUX`` or reserved characters like ``:``).
+    If set to ``ignore`` (or ``false``), no warning is printed.
+    If set to ``abort``, the command is aborted.
+    On Windows, this configuration option is ignored and the command aborted.
 ``quiet``
     Reduce the amount of output printed. True or False. Default is False.
 ``remotecmd``
diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -8,7 +8,7 @@
 from node import hex, nullid, nullrev, short
 from i18n import _
 import os, sys, errno, re, glob, tempfile
-import util, templater, patch, error, encoding, templatekw
+import util, scmutil, templater, patch, error, encoding, templatekw
 import match as matchmod
 import similar, revset, subrepo
 
@@ -435,7 +435,7 @@ def copy(ui, repo, pats, opts, rename=Fa
         src = repo.wjoin(abssrc)
         state = repo.dirstate[abstarget]
 
-        util.checkfilename(abstarget)
+        scmutil.checkportable(ui, abstarget)
 
         # check for collisions
         prevsrc = targets.get(abstarget)
diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -7,7 +7,7 @@
 
 from node import nullid, nullrev, short, hex
 from i18n import _
-import ancestor, bdiff, error, util, subrepo, patch, encoding
+import ancestor, bdiff, error, util, scmutil, subrepo, patch, encoding
 import os, errno, stat
 
 propertycache = util.propertycache
@@ -801,6 +801,7 @@ class workingctx(changectx):
         try:
             rejected = []
             for f in list:
+                scmutil.checkportable(ui, join(f))
                 p = self._repo.wjoin(f)
                 try:
                     st = os.lstat(p)
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
new file mode 100644
--- /dev/null
+++ b/mercurial/scmutil.py
@@ -0,0 +1,27 @@
+# scmutil.py - Mercurial core utility functions
+#
+#  Copyright Matt Mackall <mpm@selenic.com>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+from i18n import _
+import util, error
+import os
+
+def checkportable(ui, f):
+    '''Check if filename f is portable and warn or abort depending on config'''
+    util.checkfilename(f)
+    val = ui.config('ui', 'portablefilenames', 'warn')
+    lval = val.lower()
+    abort = os.name == 'nt' or lval == 'abort'
+    bval = util.parsebool(val)
+    if abort or lval == 'warn' or bval:
+        msg = util.checkwinfilename(f)
+        if msg:
+            if abort:
+                raise util.Abort("%s: %r" % (msg, f))
+            ui.warn(_("warning: %s: %r\n") % (msg, f))
+    elif bval is None and lval != 'ignore':
+        raise error.ConfigError(
+            _("ui.portablefilenames value is invalid ('%s')") % val)
diff --git a/tests/test-add.t b/tests/test-add.t
--- a/tests/test-add.t
+++ b/tests/test-add.t
@@ -33,6 +33,41 @@ should fail
   A a
   A b
 
+  $ echo foo > con.xml
+  $ hg --config ui.portablefilenames=jump add con.xml
+  abort: ui.portablefilenames value is invalid ('jump')
+  [255]
+  $ hg --config ui.portablefilenames=abort add con.xml
+  abort: filename contains 'con', which is reserved on Windows: 'con.xml'
+  [255]
+  $ hg st
+  A a
+  A b
+  ? con.xml
+  $ hg add con.xml
+  warning: filename contains 'con', which is reserved on Windows: 'con.xml'
+  $ hg st
+  A a
+  A b
+  A con.xml
+  $ echo bla > 'hello:world'
+  $ hg --config ui.portablefilenames=abort add
+  adding hello:world
+  abort: filename contains ':', which is reserved on Windows: 'hello:world'
+  [255]
+  $ hg st
+  A a
+  A b
+  A con.xml
+  ? hello:world
+  $ hg --config ui.portablefilenames=ignore add
+  adding hello:world
+  $ hg st
+  A a
+  A b
+  A con.xml
+  A hello:world
+
   $ hg ci -m 0 --traceback
 
 should fail
diff --git a/tests/test-addremove.t b/tests/test-addremove.t
--- a/tests/test-addremove.t
+++ b/tests/test-addremove.t
@@ -10,14 +10,17 @@
   foo
   committed changeset 0:6f7f953567a2
   $ cd dir/
-  $ touch ../foo_2 bar_2
+  $ touch ../foo_2 bar_2 con.xml
   $ hg -v addremove
   adding dir/bar_2
+  adding dir/con.xml
   adding foo_2
+  warning: filename contains 'con', which is reserved on Windows: 'dir/con.xml'
   $ hg -v commit -m "add 2"
   dir/bar_2
+  dir/con.xml
   foo_2
-  committed changeset 1:e65414bf35c5
+  committed changeset 1:6bb597da00f1
 
   $ cd ..
   $ hg init sim
diff --git a/tests/test-copy.t b/tests/test-copy.t
--- a/tests/test-copy.t
+++ b/tests/test-copy.t
@@ -4,6 +4,9 @@
   $ hg commit -m "1"
   $ hg status
   $ hg copy a b
+  $ hg --config ui.portablefilenames=abort copy a con.xml
+  abort: filename contains 'con', which is reserved on Windows: 'con.xml'
+  [255]
   $ hg status
   A b
   $ hg sum
diff --git a/tests/test-hgweb-raw.t b/tests/test-hgweb-raw.t
--- a/tests/test-hgweb-raw.t
+++ b/tests/test-hgweb-raw.t
@@ -10,6 +10,7 @@ Test raw style of hgweb
   > care about things like that.
   > ENDSOME
   $ hg add 'sub/some "text".txt'
+  warning: filename contains '"', which is reserved on Windows: 'sub/some "text".txt'
   $ hg commit -d "1 0" -m "Just some text"
 
   $ hg serve -p $HGPORT -A access.log -E error.log -d --pid-file=hg.pid
diff --git a/tests/test-rename.t b/tests/test-rename.t
--- a/tests/test-rename.t
+++ b/tests/test-rename.t
@@ -11,6 +11,9 @@
 rename a single file
 
   $ hg rename d1/d11/a1 d2/c
+  $ hg --config ui.portablefilenames=abort rename d1/a d1/con.xml
+  abort: filename contains 'con', which is reserved on Windows: 'd1/con.xml'
+  [255]
   $ hg sum
   parent: 0:9b4b6e7b2c26 tip
    1
diff --git a/tests/test-walk.t b/tests/test-walk.t
--- a/tests/test-walk.t
+++ b/tests/test-walk.t
@@ -28,6 +28,7 @@
   adding mammals/Procyonidae/coatimundi
   adding mammals/Procyonidae/raccoon
   adding mammals/skunk
+  warning: filename contains ':', which is reserved on Windows: 'glob:glob'
   $ hg commit -m "commit #0"
 
   $ hg debugwalk