diff --git a/mercurial/dummycert.pem b/mercurial/dummycert.pem
new file mode 100644
--- /dev/null
+++ b/mercurial/dummycert.pem
@@ -0,0 +1,56 @@
+A dummy certificate that will make OS X 10.6+ Python use the system CA
+certificate store:
+
+-----BEGIN CERTIFICATE-----
+MIIBIzCBzgIJANjmj39sb3FmMA0GCSqGSIb3DQEBBQUAMBkxFzAVBgNVBAMTDmhn
+LmV4YW1wbGUuY29tMB4XDTE0MDgzMDA4NDU1OVoXDTE0MDgyOTA4NDU1OVowGTEX
+MBUGA1UEAxMOaGcuZXhhbXBsZS5jb20wXDANBgkqhkiG9w0BAQEFAANLADBIAkEA
+mh/ZySGlcq0ALNLmA1gZqt61HruywPrRk6WyrLJRgt+X7OP9FFlEfl2tzHfzqvmK
+CtSQoPINWOdAJMekBYFgKQIDAQABMA0GCSqGSIb3DQEBBQUAA0EAF9h49LkSqJ6a
+IlpogZuUHtihXeKZBsiktVIDlDccYsNy0RSh9XxUfhk+XMLw8jBlYvcltSXdJ7We
+aKdQRekuMQ==
+-----END CERTIFICATE-----
+
+This certificate was generated to be syntactically valid but never be usable;
+it expired before it became valid.
+
+Created as:
+
+  $ cat > cn.conf << EOT
+  > [req]
+  > distinguished_name = req_distinguished_name
+  > [req_distinguished_name]
+  > commonName = Common Name
+  > commonName_default = no.example.com
+  > EOT
+  $ openssl req -nodes -new -x509 -keyout /dev/null \
+  >   -out dummycert.pem -days -1 -config cn.conf -subj '/CN=hg.example.com'
+
+To verify the content of this certificate:
+
+  $ openssl x509 -in dummycert.pem -noout -text
+  Certificate:
+      Data:
+          Version: 1 (0x0)
+          Serial Number: 15629337334278746470 (0xd8e68f7f6c6f7166)
+      Signature Algorithm: sha1WithRSAEncryption
+          Issuer: CN=hg.example.com
+          Validity
+              Not Before: Aug 30 08:45:59 2014 GMT
+              Not After : Aug 29 08:45:59 2014 GMT
+          Subject: CN=hg.example.com
+          Subject Public Key Info:
+              Public Key Algorithm: rsaEncryption
+                  Public-Key: (512 bit)
+                  Modulus:
+                      00:9a:1f:d9:c9:21:a5:72:ad:00:2c:d2:e6:03:58:
+                      19:aa:de:b5:1e:bb:b2:c0:fa:d1:93:a5:b2:ac:b2:
+                      51:82:df:97:ec:e3:fd:14:59:44:7e:5d:ad:cc:77:
+                      f3:aa:f9:8a:0a:d4:90:a0:f2:0d:58:e7:40:24:c7:
+                      a4:05:81:60:29
+                  Exponent: 65537 (0x10001)
+      Signature Algorithm: sha1WithRSAEncryption
+           17:d8:78:f4:b9:12:a8:9e:9a:22:5a:68:81:9b:94:1e:d8:a1:
+           5d:e2:99:06:c8:a4:b5:52:03:94:37:1c:62:c3:72:d1:14:a1:
+           f5:7c:54:7e:19:3e:5c:c2:f0:f2:30:65:62:f7:25:b5:25:dd:
+           27:b5:9e:68:a7:50:45:e9:2e:31
diff --git a/mercurial/sslutil.py b/mercurial/sslutil.py
--- a/mercurial/sslutil.py
+++ b/mercurial/sslutil.py
@@ -6,7 +6,7 @@
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
-import os
+import os, sys
 
 from mercurial import util
 from mercurial.i18n import _
@@ -104,6 +104,13 @@ def sslkwargs(ui, host):
         cacerts = util.expandpath(cacerts)
         if not os.path.exists(cacerts):
             raise util.Abort(_('could not find web.cacerts: %s') % cacerts)
+    elif cacerts is None and sys.platform == 'darwin' and not util.mainfrozen():
+        dummycert = os.path.join(os.path.dirname(__file__), 'dummycert.pem')
+        if os.path.exists(dummycert):
+            ui.debug('using %s to enable OS X system CA\n' % dummycert)
+            ui.setconfig('web', 'cacerts', dummycert, 'dummy')
+            cacerts = dummycert
+    if cacerts:
         kws.update({'ca_certs': cacerts,
                     'cert_reqs': CERT_REQUIRED,
                     })
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -481,7 +481,8 @@ class HackedMingw32CCompiler(cygwinccomp
 cygwinccompiler.Mingw32CCompiler = HackedMingw32CCompiler
 
 packagedata = {'mercurial': ['locale/*/LC_MESSAGES/hg.mo',
-                             'help/*.txt']}
+                             'help/*.txt',
+                             'dummycert.pem']}
 
 def ordinarypath(p):
     return p and p[0] != '.' and p[-1] != '~'
diff --git a/tests/hghave.py b/tests/hghave.py
--- a/tests/hghave.py
+++ b/tests/hghave.py
@@ -332,6 +332,10 @@ def has_msys():
 def has_aix():
     return sys.platform.startswith("aix")
 
+@check("osx", "OS X")
+def has_osx():
+    return sys.platform == 'darwin'
+
 @check("absimport", "absolute_import in __future__")
 def has_absimport():
     import __future__
diff --git a/tests/test-https.t b/tests/test-https.t
--- a/tests/test-https.t
+++ b/tests/test-https.t
@@ -115,9 +115,20 @@ Test server address cannot be reused
 #endif
   $ cd ..
 
+OS X has a dummy CA cert that enables use of the system CA store
+
+  $ DISABLEOSXDUMMYCERT=
+#if osx
+  $ hg clone https://localhost:$HGPORT/ copy-pull
+  abort: error: *:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed (glob)
+  [255]
+
+  $ DISABLEOSXDUMMYCERT="--config=web.cacerts="
+#endif
+
 clone via pull
 
-  $ hg clone https://localhost:$HGPORT/ copy-pull
+  $ hg clone https://localhost:$HGPORT/ copy-pull $DISABLEOSXDUMMYCERT
   warning: localhost certificate with fingerprint 91:4f:1a:ff:87:24:9c:09:b6:85:9b:88:b1:90:6d:30:75:64:91:ca not verified (check hostfingerprints or web.cacerts config setting)
   requesting all changes
   adding changesets
@@ -143,7 +154,7 @@ pull without cacert
   $ cd copy-pull
   $ echo '[hooks]' >> .hg/hgrc
   $ echo "changegroup = python \"$TESTDIR/printenv.py\" changegroup" >> .hg/hgrc
-  $ hg pull
+  $ hg pull $DISABLEOSXDUMMYCERT
   warning: localhost certificate with fingerprint 91:4f:1a:ff:87:24:9c:09:b6:85:9b:88:b1:90:6d:30:75:64:91:ca not verified (check hostfingerprints or web.cacerts config setting)
   pulling from https://localhost:$HGPORT/
   searching for changes