diff --git a/doc/source/usage.rst b/doc/source/usage.rst
index 7aba41f..d16a2ee 100644
--- a/doc/source/usage.rst
+++ b/doc/source/usage.rst
@@ -44,6 +44,22 @@ Rendering the `example.spec.j2` file and also use the epochs can be done with::
           The epoch file is optional. If a package name is not in the epochs file,
           epoch for that package is not used.
 
+Handling requirements
+*********************
+
+Updating versions for `Requires` and `BuildRequires` takes a lot of time.
+:program:`renderspec` has the ability to insert versions from a given
+`global-requirements.txt` file. The file must contain lines following `PEP0508`_
+
+.. note:: For OpenStack, the `global-requirements.txt`_ can be used.
+
+To render a `example.spec.j2` file with a given requirements file, do::
+
+  renderspec --requirements global-requirements.txt example.spec.j2
+
+.. _PEP0508: https://www.python.org/dev/peps/pep-0508/
+.. _global-requirements.txt: https://git.openstack.org/cgit/openstack/requirements/tree/global-requirements.txt
+
 Template features
 =================
 
@@ -79,6 +95,11 @@ rendered on Fedora to::
 
   BuildRequires:  python-oslo-config >= 2:3.4.0
 
+It's also possible to skip adding required versions and handle that with a
+`global-requirements.txt` file. Given that this file contains `oslo.config>=4.3.0` and
+rendering with `--requirements`, the rendered spec would contain::
+
+  BuildRequires:  python-oslo-config >= 4.3.0
 
 context filter `license`
 ************************
diff --git a/renderspec/__init__.py b/renderspec/__init__.py
index ce2f71e..5963383 100644
--- a/renderspec/__init__.py
+++ b/renderspec/__init__.py
@@ -29,17 +29,24 @@ import pymod2pkg
 
 import yaml
 
+from renderspec import versions
+
 
 def _context_epoch(context, pkg_name):
     """get the epoch (or 0 if unknown) for the given pkg name"""
     return context['epochs'].get(pkg_name, 0)
 
 
-def _context_py2pkg(context, pkg_name, pkg_version=None):
+def _context_py2pkg(context, pkg_name, pkg_version=None, old_filter=False):
     """generate a distro specific package name with optional version tuple."""
     # package name handling
     name = pymod2pkg.module2package(pkg_name, context['spec_style'])
 
+    # if no pkg_version is given, look in the requirements and set one
+    if not pkg_version and not old_filter:
+        if pkg_name in context['requirements']:
+            pkg_version = ('>=', context['requirements'][pkg_name])
+
     # pkg_version is a tuple with comparator and number, i.e. "('>=', '1.2.3')"
     if pkg_version:
         # epoch handling
@@ -103,7 +110,7 @@ def _filter_epoch(context, value):
 
 @contextfilter
 def _filter_python_module2package(context, pkg_name, pkg_version=None):
-    return _context_py2pkg(context, pkg_name, pkg_version)
+    return _context_py2pkg(context, pkg_name, pkg_version, old_filter=True)
 
 
 ################
@@ -134,7 +141,7 @@ def _env_register_filters_and_globals(env):
     env.globals['license'] = _globals_license_spdx
 
 
-def generate_spec(spec_style, epochs, input_template_path):
+def generate_spec(spec_style, epochs, requirements, input_template_path):
     """generate a spec file with the given style and the given template"""
     env = Environment(loader=FileSystemLoader(
         os.path.dirname(input_template_path)))
@@ -142,7 +149,8 @@ def generate_spec(spec_style, epochs, input_template_path):
     _env_register_filters_and_globals(env)
 
     template = env.get_template(os.path.basename(input_template_path))
-    return template.render(spec_style=spec_style, epochs=epochs)
+    return template.render(spec_style=spec_style, epochs=epochs,
+                           requirements=requirements)
 
 
 def _get_default_distro():
@@ -178,6 +186,14 @@ def _get_epochs(filename):
     return {}
 
 
+def _get_requirements(filename):
+    """get a dictionary with pkg-name->min-version mapping"""
+    if os.path.exists(filename):
+        with open(filename, 'r') as f:
+            return versions.get_requirements(f.readlines())
+    return {}
+
+
 def process_args():
     distro = _get_default_distro()
     parser = argparse.ArgumentParser(
@@ -194,6 +210,11 @@ def process_args():
     parser.add_argument("input-template", nargs='?',
                         help="specfile jinja2 template to render. "
                         "default: *.spec.j2")
+    parser.add_argument("--requirements", help="file which contains "
+                        "PEP0508 compatible requirement lines."
+                        "default: global-requirements.txt",
+                        default="global-requirements.txt")
+
     return vars(parser.parse_args())
 
 
@@ -216,7 +237,9 @@ def main():
         output_fn, _, _ = input_template.rpartition('.')
 
     epochs = _get_epochs(args['epochs'])
-    spec = generate_spec(args['spec_style'], epochs, input_template)
+    requirements = _get_requirements(args['requirements'])
+    spec = generate_spec(args['spec_style'], epochs, requirements,
+                         input_template)
     if output_fn and output_fn != '-':
         print("Rendering: %s -> %s" % (input_template, output_fn))
         with open(output_fn, "w") as o:
diff --git a/renderspec/versions.py b/renderspec/versions.py
new file mode 100644
index 0000000..ee68cdc
--- /dev/null
+++ b/renderspec/versions.py
@@ -0,0 +1,54 @@
+#!/usr/bin/python
+# Copyright (c) 2016 SUSE Linux GmbH
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+
+from packaging.requirements import Requirement
+
+
+def get_requirements(lines):
+    """parse the given lines and return a dict with pkg_name->version.
+    lines must follow PEP0508"""
+    requires = {}
+    for l in lines:
+        # skip comments and empty lines
+        if l.startswith('#') or len(l.strip()) == 0:
+            continue
+        # remove trailing comments
+        l = l.split('#')[0].rstrip(' ')
+        r = Requirement(l)
+        # check if we need the requirement
+        if r.marker:
+            # TODO (toabctl): currently we hardcode python 2.7 and linux2
+            # see https://www.python.org/dev/peps/pep-0508/#environment-markers
+            marker_env = {'python_version': '2.7', 'sys_platform': 'linux'}
+            if not r.marker.evaluate(environment=marker_env):
+                continue
+        if r.specifier:
+            # we want the lowest possible version
+            # NOTE(toabctl): "min(r.specifier)" doesn't work.
+            # see https://github.com/pypa/packaging/issues/69
+            lowest = None
+            for s in r.specifier:
+                # we don't want a lowest version which is not allowed
+                if s.operator == '!=':
+                    continue
+                if not lowest or s.version < lowest.version:
+                    lowest = s
+
+            if lowest:
+                requires[r.name] = lowest.version
+    return requires
diff --git a/requirements.txt b/requirements.txt
index ea0303a..8502e2f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
 Jinja2>=2.6
 pymod2pkg>=0.3
 PyYAML>=3.1.0  # MIT
+packaging>=16.5
diff --git a/test-requirements.txt b/test-requirements.txt
index 13057b8..ac8d484 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -2,6 +2,7 @@ flake8
 testrepository>=0.0.18
 testresources>=0.2.4
 testtools>=1.4.0
+ddt
 
 sphinx!=1.2.0,!=1.3b1,<1.3,>=1.1.2
 oslosphinx!=3.4.0,>=2.5.0 # Apache-2.0
diff --git a/tests.py b/tests.py
index 4ad1216..1e3811e 100644
--- a/tests.py
+++ b/tests.py
@@ -20,11 +20,15 @@ try:
 except ImportError:
     import unittest
 
+from ddt import data, ddt, unpack
+
 from jinja2 import Environment
 
 import renderspec
+import renderspec.versions
 
 
+@ddt
 class RenderspecContextFunctionTests(unittest.TestCase):
     """test functions which do some calculation based on the context"""
     def test_context_license_spdx(self):
@@ -39,112 +43,88 @@ class RenderspecContextFunctionTests(unittest.TestCase):
             'ASL 2.0'
         )
 
-    def test_context_py2pkg_pgkname_only(self):
+    @data(
+        # without version
+        ({'spec_style': 'suse', 'epochs': {}, 'requirements': {}},
+         'oslo.config', None, 'python-oslo.config'),
+        ({'spec_style': 'fedora', 'epochs': {}, 'requirements': {}},
+         'oslo.config', None, 'python-oslo-config'),
+        # with version
+        ({'spec_style': 'suse', 'epochs': {}, 'requirements': {}},
+         'oslo.config', ('>=', '1.2.3'), 'python-oslo.config >= 1.2.3'),
+        ({'spec_style': 'fedora', 'epochs': {}, 'requirements': {}},
+         'oslo.config', ('==', '1.2.3~a0'), 'python-oslo-config == 1.2.3~a0'),
+        # with version, with epoch
+        ({'spec_style': 'suse', 'epochs': {'oslo.config': 4},
+          'requirements': {}},
+         'oslo.config', ('>=', '1.2.3'), 'python-oslo.config >= 4:1.2.3'),
+        # without version, with epoch
+        ({'spec_style': 'suse', 'epochs': {'oslo.config': 4},
+          'requirements': {}},
+         'oslo.config', None, 'python-oslo.config'),
+        # with version, with requirements
+        ({'spec_style': 'suse', 'epochs': {},
+          'requirements': {'oslo.config' '1.2.3'}},
+         'oslo.config', ('>=', '4.5.6'), 'python-oslo.config >= 4.5.6'),
+        # without version, with requirements
+        ({'spec_style': 'suse', 'epochs': {},
+          'requirements': {'oslo.config': '1.2.3'}},
+         'oslo.config', None, 'python-oslo.config >= 1.2.3'),
+        # without version, with requirements, with epoch
+        ({'spec_style': 'suse', 'epochs': {'oslo.config': 4},
+          'requirements': {'oslo.config': '1.2.3'}},
+         'oslo.config', None, 'python-oslo.config >= 4:1.2.3'),
+        # with version, with requirements, with epoch
+        ({'spec_style': 'suse', 'epochs': {'oslo.config': 4},
+          'requirements': {'oslo.config' '1.2.3'}},
+         'oslo.config', ('>=', '4.5.6'), 'python-oslo.config >= 4:4.5.6'),
+    )
+    @unpack
+    def test_context_py2pkg(self, context, pkg_name, pkg_version,
+                            expected_result):
         self.assertEqual(
-            renderspec._context_py2pkg(
-                {'spec_style': 'suse', 'epochs': {}}, 'oslo.config'),
-            'python-oslo.config'
-        )
-        self.assertEqual(
-            renderspec._context_py2pkg(
-                {'spec_style': 'fedora', 'epochs': {}}, 'oslo.config'),
-            'python-oslo-config'
-        )
-
-    def test_context_py2pkg_pgkname_and_version(self):
-        self.assertEqual(
-            renderspec._context_py2pkg(
-                {'spec_style': 'suse', 'epochs': {}},
-                'oslo.config', ('>=', '1.2.3')),
-            'python-oslo.config >= 1.2.3'
-        )
-        self.assertEqual(
-            renderspec._context_py2pkg(
-                {'spec_style': 'fedora', 'epochs': {}},
-                'oslo.config', ('==', '1.2.3~a0')),
-            'python-oslo-config == 1.2.3~a0'
-        )
-
-    def test_context_py2pkg_pgkname_and_version_and_epoch(self):
-        self.assertEqual(
-            renderspec._context_py2pkg(
-                {'spec_style': 'suse', 'epochs': {'oslo.config': '4'}},
-                'oslo.config', ('>=', '1.2.3')),
-            'python-oslo.config >= 4:1.2.3'
-        )
-
-    def test_context_py2pkg_pgkname_and_epoch_no_version(self):
-        self.assertEqual(
-            renderspec._context_py2pkg(
-                {'spec_style': 'suse', 'epochs': {'oslo.config': '4'}},
-                'oslo.config'),
-            'python-oslo.config'
-        )
+            renderspec._context_py2pkg(context, pkg_name, pkg_version),
+            expected_result)
 
     def test_context_epoch_without_epochs(self):
         self.assertEqual(
             renderspec._context_epoch(
-                {'spec_style': 'suse', 'epochs': {}}, 'oslo.config'),
-            0
-        )
+                {'spec_style': 'suse', 'epochs': {}, 'requirements': {}},
+                'oslo.config'), 0)
 
     def test_context_epoch_with_epochs(self):
         self.assertEqual(
             renderspec._context_epoch(
-                {'spec_style': 'suse', 'epochs': {'oslo.config': 4}},
-                'oslo.config'),
-            4
-        )
+                {'spec_style': 'suse', 'epochs': {'oslo.config': 4},
+                 'requirements': {}}, 'oslo.config'), 4)
 
 
+@ddt
 class RenderspecTemplateFilterTests(unittest.TestCase):
     def setUp(self):
         """create a Jinja2 environment and register the standard filters"""
         self.env = Environment()
         renderspec._env_register_filters_and_globals(self.env)
 
-    def test_render_filter_py2pkg_oldstyle(self):
-        template = self.env.from_string("{{ 'requests' | py2pkg }} >= 2.8.1")
+    @data(
+        # old style
+        ({'spec_style': 'suse', 'epochs': {}, 'requirements': {}},
+         "{{ 'requests' | py2pkg }}", "python-requests"),
+        ({'spec_style': 'suse', 'epochs': {}, 'requirements': {}},
+         "{{ 'requests' | py2pkg }} >= 2.8.1", "python-requests >= 2.8.1"),
+        ({'spec_style': 'suse', 'epochs': {},
+          'requirements': {'requests': '1.2.3'}},
+         "{{ 'requests' | py2pkg }} >= 2.8.1", "python-requests >= 2.8.1"),
+    )
+    @unpack
+    def test_render_filter_py2pkg(self, context, string, expected_result):
+        template = self.env.from_string(string)
         self.assertEqual(
-            template.render(spec_style='suse', epochs={}),
-            'python-requests >= 2.8.1')
-
-    def test_render_filter_py2pkg(self):
-        template = self.env.from_string(
-            "{{ 'requests' | py2pkg }}")
-        self.assertEqual(
-            template.render(spec_style='suse', epochs={}),
-            'python-requests')
-
-    def test_render_filter_py2pkg_with_version(self):
-        template = self.env.from_string(
-            "{{ 'requests' | py2pkg(('>=', '2.8.1')) }}")
-        self.assertEqual(
-            template.render(spec_style='suse', epochs={}),
-            'python-requests >= 2.8.1')
-
-    def test_render_filter_py2pkg_with_version_and_epoch(self):
-        template = self.env.from_string(
-            "{{ 'requests' | py2pkg(('>=', '2.8.1')) }}")
-        self.assertEqual(
-            template.render(spec_style='suse', epochs={'requests': '1'}),
-            'python-requests >= 1:2.8.1')
-
-    def test_render_filter_epoch_without_epochs(self):
-        template = self.env.from_string(
-            "{{ 'requests' | epoch }}")
-        self.assertEqual(
-            template.render(spec_style='suse', epochs={}),
-            '0')
-
-    def test_render_filter_epoch_with_epochs(self):
-        template = self.env.from_string(
-            "{{ 'requests' | epoch }}")
-        self.assertEqual(
-            template.render(spec_style='suse', epochs={'requests': '1'}),
-            '1')
+            template.render(**context),
+            expected_result)
 
 
+@ddt
 class RenderspecTemplateFunctionTests(unittest.TestCase):
     def setUp(self):
         """create a Jinja2 environment and register the standard filters"""
@@ -155,44 +135,88 @@ class RenderspecTemplateFunctionTests(unittest.TestCase):
         template = self.env.from_string(
             "{{ license('Apache-2.0') }}")
         self.assertEqual(
-            template.render(spec_style='fedora', epochs={}),
+            template.render(spec_style='fedora', epochs={}, requirements={}),
             'ASL 2.0')
 
-    def test_render_func_py2pkg(self):
-        template = self.env.from_string(
-            "{{ py2pkg('requests') }}")
-        self.assertEqual(
-            template.render(spec_style='suse', epochs={}),
-            'python-requests')
+    @data(
+        # plain
+        ({'spec_style': 'suse', 'epochs': {}, 'requirements': {}},
+         "{{ py2pkg('requests') }}", "python-requests"),
+        # with version
+        ({'spec_style': 'suse', 'epochs': {}, 'requirements': {}},
+         "{{ py2pkg('requests', ('>=', '2.8.1')) }}",
+         "python-requests >= 2.8.1"),
+        # with version, with epoch
+        ({'spec_style': 'suse', 'epochs': {'requests': 4}, 'requirements': {}},
+         "{{ py2pkg('requests', ('>=', '2.8.1')) }}",
+         "python-requests >= 4:2.8.1"),
+        # with version, with epoch, with requirements
+        ({'spec_style': 'suse', 'epochs': {'requests': 4},
+          'requirements': {'requests': '1.2.3'}},
+         "{{ py2pkg('requests', ('>=', '2.8.1')) }}",
+         "python-requests >= 4:2.8.1"),
+        # without version, with epoch, with requirements
+        ({'spec_style': 'suse', 'epochs': {'requests': 4},
+          'requirements': {'requests': '1.2.3'}},
+         "{{ py2pkg('requests') }}",
+         "python-requests >= 4:1.2.3"),
 
-    def test_render_func_py2pkg_with_version(self):
-        template = self.env.from_string(
-            "{{ py2pkg('requests', ('>=', '2.8.1')) }}")
+    )
+    @unpack
+    def test_render_func_py2pkg(self, context, string, expected_result):
+        template = self.env.from_string(string)
         self.assertEqual(
-            template.render(spec_style='suse', epochs={}),
-            'python-requests >= 2.8.1')
-
-    def test_render_func_py2pkg_with_version_and_epoch(self):
-        template = self.env.from_string(
-            "{{ py2pkg('requests', ('>=', '2.8.1')) }}")
-        self.assertEqual(
-            template.render(spec_style='suse', epochs={'requests': '1'}),
-            'python-requests >= 1:2.8.1')
+            template.render(**context),
+            expected_result)
 
     def test_render_func_epoch_without_epochs(self):
         template = self.env.from_string(
             "Epoch: {{ epoch('requests') }}")
         self.assertEqual(
-            template.render(spec_style='suse', epochs={}),
+            template.render(spec_style='suse', epochs={}, requirements={}),
             'Epoch: 0')
 
     def test_render_func_epoch_with_epochs(self):
         template = self.env.from_string(
             "Epoch: {{ epoch('requests') }}")
         self.assertEqual(
-            template.render(spec_style='suse', epochs={'requests': 1}),
+            template.render(spec_style='suse', epochs={'requests': 1},
+                            requirements={}),
             'Epoch: 1')
 
 
+class RenderspecVersionsTests(unittest.TestCase):
+    def test_without_version(self):
+        requires = renderspec.versions.get_requirements(
+            ['# a comment', '', '   ', 'pyasn1  # BSD', 'Paste'])
+        self.assertEqual(requires, {})
+
+    def test_with_single_version(self):
+        requires = renderspec.versions.get_requirements(
+            ['paramiko>=1.16.0  # LGPL'])
+        self.assertEqual(requires, {'paramiko': '1.16.0'})
+
+    def test_with_multiple_versions(self):
+        requires = renderspec.versions.get_requirements(
+            ['sphinx>=1.1.2,!=1.2.0,!=1.3b1,<1.3  # BSD'])
+        self.assertEqual(requires, {'sphinx': '1.1.2'})
+
+    def test_with_multiple_versions_and_invalid_lowest(self):
+        requires = renderspec.versions.get_requirements(
+            ['sphinx>=1.1.2,!=1.1.0,!=1.3b1,<1.3  # BSD'])
+        self.assertEqual(requires, {'sphinx': '1.1.2'})
+
+    def test_with_single_marker(self):
+        requires = renderspec.versions.get_requirements(
+            ["pywin32>=1.0;sys_platform=='win32'  # PSF"])
+        self.assertEqual(requires, {})
+
+    def test_with_multiple_markers(self):
+        requires = renderspec.versions.get_requirements(
+            ["""pyinotify>=0.9.6;sys_platform!='win32' and \
+            sys_platform!='darwin' and sys_platform!='sunos5' # MIT"""])
+        self.assertEqual(requires, {'pyinotify': '0.9.6'})
+
+
 if __name__ == '__main__':
     unittest.main()