diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -1270,6 +1270,9 @@
     b'ui', b'editor', default=dynamicdefault,
 )
 coreconfigitem(
+    b'ui', b'detailed-exit-code', default=False, experimental=True,
+)
+coreconfigitem(
     b'ui', b'fallbackencoding', default=None,
 )
 coreconfigitem(
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -148,6 +148,8 @@
     return func() if no exception happens. otherwise do some error handling
     and return an exit code accordingly. does not handle all exceptions.
     """
+    want_detailed_exit_code = ui.configbool(b'ui', b'detailed-exit-code')
+    exit_code = -1
     try:
         try:
             return func()
@@ -216,6 +218,9 @@
     except error.WdirUnsupported:
         ui.error(_(b"abort: working directory revision cannot be specified\n"))
     except error.Abort as inst:
+        if want_detailed_exit_code:
+            # TODO: set exit_code for different errors here
+            pass
         ui.error(_(b"abort: %s\n") % inst.message)
         if inst.hint:
             ui.error(_(b"(%s)\n") % inst.hint)
@@ -265,7 +270,7 @@
         # Just in case catch this and and pass exit code to caller.
         return inst.code
 
-    return -1
+    return exit_code
 
 
 def checknewlabel(repo, lbl, kind):
diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -60,6 +60,8 @@
 # The config knobs that will be altered (if unset) by ui.tweakdefaults.
 tweakrc = b"""
 [ui]
+# Gives detailed exit codes for input/user errors, config errors, etc.
+detailed-exit-code = True
 # The rollback command is dangerous. As a rule, don't use it.
 rollback = False
 # Make `hg status` report copy information
diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -1439,6 +1439,7 @@
             hgrc.write(b'[ui]\n')
             hgrc.write(b'slash = True\n')
             hgrc.write(b'interactive = False\n')
+            hgrc.write(b'detailed-exit-code = True\n')
             hgrc.write(b'merge = internal:merge\n')
             hgrc.write(b'mergemarkers = detailed\n')
             hgrc.write(b'promptecho = True\n')
diff --git a/tests/test-basic.t b/tests/test-basic.t
--- a/tests/test-basic.t
+++ b/tests/test-basic.t
@@ -9,6 +9,7 @@
   lfs.usercache=$TESTTMP/.cache/lfs
   ui.slash=True
   ui.interactive=False
+  ui.detailed-exit-code=True
   ui.merge=internal:merge
   ui.mergemarkers=detailed
   ui.promptecho=True
diff --git a/tests/test-commandserver.t b/tests/test-commandserver.t
--- a/tests/test-commandserver.t
+++ b/tests/test-commandserver.t
@@ -211,6 +211,7 @@
   lfs.usercache=$TESTTMP/.cache/lfs
   ui.slash=True
   ui.interactive=False
+  ui.detailed-exit-code=True
   ui.merge=internal:merge
   ui.mergemarkers=detailed
   ui.foo=bar
@@ -222,6 +223,7 @@
   *** runcommand -R foo showconfig ui defaults
   ui.slash=True
   ui.interactive=False
+  ui.detailed-exit-code=True
   ui.merge=internal:merge
   ui.mergemarkers=detailed
   ui.nontty=true
diff --git a/tests/test-legacy-exit-code.t b/tests/test-legacy-exit-code.t
new file mode 100644
--- /dev/null
+++ b/tests/test-legacy-exit-code.t
@@ -0,0 +1,35 @@
+Tests that the exit code is as expected when ui.detailed-exit-code is *not*
+enabled.
+
+  $ hg init
+  $ echo a > a
+Expect exit code 0 on success
+  $ hg ci -Aqm initial
+
+  $ hg co nonexistent
+  abort: unknown revision 'nonexistent'!
+  [255]
+
+  $ hg co 'none()'
+  abort: empty revision set
+  [255]
+
+  $ hg co 'invalid('
+  hg: parse error at 8: not a prefix: end
+  (invalid(
+           ^ here)
+  [255]
+
+  $ hg co 'invalid('
+  hg: parse error at 8: not a prefix: end
+  (invalid(
+           ^ here)
+  [255]
+
+  $ hg continue
+  abort: no operation in progress
+  [255]
+
+  $ hg st --config a=b
+  abort: malformed --config option: 'a=b' (use --config section.name=value)
+  [255]