diff --git a/NEWS b/NEWS
index 72ef09b71..d8a3e8019 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,8 @@
+1.4.7
+ * #239: Upgrade your borgmatic configuration to get new options and comments via
+   "generate-borgmatic-config --source". See the documentation for more information:
+   https://torsion.org/borgmatic/docs/how-to/upgrade/#upgrading-your-configuration
+
 1.4.6
  * Verbosity level "-1" for even quieter output: Errors only (#236).
 
diff --git a/borgmatic/commands/generate_config.py b/borgmatic/commands/generate_config.py
index f338f3033..8ea3d5c13 100644
--- a/borgmatic/commands/generate_config.py
+++ b/borgmatic/commands/generate_config.py
@@ -12,12 +12,18 @@ def parse_arguments(*arguments):
     them as an ArgumentParser instance.
     '''
     parser = ArgumentParser(description='Generate a sample borgmatic YAML configuration file.')
+    parser.add_argument(
+        '-s',
+        '--source',
+        dest='source_filename',
+        help='Optional YAML configuration file to merge into the generated configuration, useful for upgrading your configuration',
+    )
     parser.add_argument(
         '-d',
         '--destination',
         dest='destination_filename',
         default=DEFAULT_DESTINATION_CONFIG_FILENAME,
-        help='Destination YAML configuration filename. Default: {}'.format(
+        help='Destination YAML configuration file. Default: {}'.format(
             DEFAULT_DESTINATION_CONFIG_FILENAME
         ),
     )
@@ -30,11 +36,21 @@ def main():  # pragma: no cover
         args = parse_arguments(*sys.argv[1:])
 
         generate.generate_sample_configuration(
-            args.destination_filename, validate.schema_filename()
+            args.source_filename, args.destination_filename, validate.schema_filename()
         )
 
         print('Generated a sample configuration file at {}.'.format(args.destination_filename))
         print()
+        if args.source_filename:
+            print(
+                'Merged in the contents of configuration file at {}.'.format(args.source_filename)
+            )
+            print('To review the changes made, run:')
+            print()
+            print(
+                '    diff --unified {} {}'.format(args.source_filename, args.destination_filename)
+            )
+            print()
         print('Please edit the file to suit your needs. The values are representative.')
         print('All fields are optional except where indicated.')
         print()
diff --git a/borgmatic/config/generate.py b/borgmatic/config/generate.py
index c0399ed2c..05bbd367c 100644
--- a/borgmatic/config/generate.py
+++ b/borgmatic/config/generate.py
@@ -1,9 +1,12 @@
+import collections
 import io
 import os
 import re
 
 from ruamel import yaml
 
+from borgmatic.config import load
+
 INDENT = 4
 SEQUENCE_INDENT = 2
 
@@ -40,8 +43,8 @@ def _schema_to_sample_configuration(schema, level=0, parent_is_sequence=False):
     elif 'map' in schema:
         config = yaml.comments.CommentedMap(
             [
-                (section_name, _schema_to_sample_configuration(section_schema, level + 1))
-                for section_name, section_schema in schema['map'].items()
+                (field_name, _schema_to_sample_configuration(sub_schema, level + 1))
+                for field_name, sub_schema in schema['map'].items()
             ]
         )
         indent = (level * INDENT) + (SEQUENCE_INDENT if parent_is_sequence else 0)
@@ -68,37 +71,32 @@ def _comment_out_line(line):
     return '# '.join((indent_spaces, line[count_indent_spaces:]))
 
 
-REQUIRED_KEYS = {'source_directories', 'repositories', 'keep_daily'}
-REQUIRED_SECTION_NAMES = {'location', 'retention'}
-
-
 def _comment_out_optional_configuration(rendered_config):
     '''
-    Post-process a rendered configuration string to comment out optional key/values. The idea is
-    that this prevents the user from having to comment out a bunch of configuration they don't care
-    about to get to a minimal viable configuration file.
+    Post-process a rendered configuration string to comment out optional key/values, as determined
+    by a sentinel in the comment before each key.
 
-    Ideally ruamel.yaml would support this during configuration generation, but it's not terribly
-    easy to accomplish that way.
+    The idea is that the pre-commented configuration prevents the user from having to comment out a
+    bunch of configuration they don't care about to get to a minimal viable configuration file.
+
+    Ideally ruamel.yaml would support commenting out keys during configuration generation, but it's
+    not terribly easy to accomplish that way.
     '''
     lines = []
-    required = False
+    optional = False
 
     for line in rendered_config.split('\n'):
-        key = line.strip().split(':')[0]
-
-        if key in REQUIRED_SECTION_NAMES:
-            lines.append(line)
+        # Upon encountering an optional configuration option, commenting out lines until the next
+        # blank line.
+        if line.strip().startswith('# {}'.format(COMMENTED_OUT_SENTINEL)):
+            optional = True
             continue
 
-        # Upon encountering a required configuration option, skip commenting out lines until the
-        # next blank line.
-        if key in REQUIRED_KEYS:
-            required = True
-        elif not key:
-            required = False
+        # Hit a blank line, so reset commenting.
+        if not line.strip():
+            optional = False
 
-        lines.append(_comment_out_line(line) if not required else line)
+        lines.append(_comment_out_line(line) if optional else line)
 
     return '\n'.join(lines)
 
@@ -168,6 +166,11 @@ def add_comments_to_configuration_sequence(config, schema, indent=0):
         return
 
 
+REQUIRED_SECTION_NAMES = {'location', 'retention'}
+REQUIRED_KEYS = {'source_directories', 'repositories', 'keep_daily'}
+COMMENTED_OUT_SENTINEL = 'COMMENT_OUT'
+
+
 def add_comments_to_configuration_map(config, schema, indent=0, skip_first=False):
     '''
     Using descriptions from a schema as a source, add those descriptions as comments to the given
@@ -178,10 +181,20 @@ def add_comments_to_configuration_map(config, schema, indent=0, skip_first=False
             continue
 
         field_schema = schema['map'].get(field_name, {})
-        description = field_schema.get('desc')
+        description = field_schema.get('desc', '').strip()
+
+        # If this is an optional key, add an indicator to the comment flagging it to be commented
+        # out from the sample configuration. This sentinel is consumed by downstream processing that
+        # does the actual commenting out.
+        if field_name not in REQUIRED_SECTION_NAMES and field_name not in REQUIRED_KEYS:
+            description = (
+                '\n'.join((description, COMMENTED_OUT_SENTINEL))
+                if description
+                else COMMENTED_OUT_SENTINEL
+            )
 
         # No description to use? Skip it.
-        if not field_schema or not description:
+        if not field_schema or not description:  # pragma: no cover
             continue
 
         config.yaml_set_comment_before_after_key(key=field_name, before=description, indent=indent)
@@ -190,14 +203,86 @@ def add_comments_to_configuration_map(config, schema, indent=0, skip_first=False
             _insert_newline_before_comment(config, field_name)
 
 
-def generate_sample_configuration(config_filename, schema_filename):
+RUAMEL_YAML_COMMENTS_INDEX = 1
+
+
+def remove_commented_out_sentinel(config, field_name):
     '''
-    Given a target config filename and the path to a schema filename in pykwalify YAML schema
-    format, write out a sample configuration file based on that schema.
+    Given a configuration CommentedMap and a top-level field name in it, remove any "commented out"
+    sentinel found at the end of its YAML comments. This prevents the given field name from getting
+    commented out by downstream processing that consumes the sentinel.
+    '''
+    try:
+        last_comment_value = config.ca.items[field_name][RUAMEL_YAML_COMMENTS_INDEX][-1].value
+    except KeyError:
+        return
+
+    if last_comment_value == '# {}\n'.format(COMMENTED_OUT_SENTINEL):
+        config.ca.items[field_name][RUAMEL_YAML_COMMENTS_INDEX].pop()
+
+
+def merge_source_configuration_into_destination(destination_config, source_config):
+    '''
+    Deep merge the given source configuration dict into the destination configuration CommentedMap,
+    favoring values from the source when there are collisions.
+
+    The purpose of this is to upgrade configuration files from old versions of borgmatic by adding
+    new
+    configuration keys and comments.
+    '''
+    if not destination_config or not isinstance(source_config, collections.abc.Mapping):
+        return source_config
+
+    for field_name, source_value in source_config.items():
+        # Since this key/value is from the source configuration, leave it uncommented and remove any
+        # sentinel that would cause it to get commented out.
+        remove_commented_out_sentinel(destination_config, field_name)
+
+        # This is a mapping. Recurse for this key/value.
+        if isinstance(source_value, collections.abc.Mapping):
+            destination_config[field_name] = merge_source_configuration_into_destination(
+                destination_config[field_name], source_value
+            )
+            continue
+
+        # This is a sequence. Recurse for each item in it.
+        if isinstance(source_value, collections.abc.Sequence) and not isinstance(source_value, str):
+            destination_value = destination_config[field_name]
+            destination_config[field_name] = yaml.comments.CommentedSeq(
+                [
+                    merge_source_configuration_into_destination(
+                        destination_value[index] if index < len(destination_value) else None,
+                        source_item,
+                    )
+                    for index, source_item in enumerate(source_value)
+                ]
+            )
+            continue
+
+        # This is some sort of scalar. Simply set it into the destination.
+        destination_config[field_name] = source_config[field_name]
+
+    return destination_config
+
+
+def generate_sample_configuration(source_filename, destination_filename, schema_filename):
+    '''
+    Given an optional source configuration filename, and a required destination configuration
+    filename, and the path to a schema filename in pykwalify YAML schema format, write out a
+    sample configuration file based on that schema. If a source filename is provided, merge the
+    parsed contents of that configuration into the generated configuration.
     '''
     schema = yaml.round_trip_load(open(schema_filename))
-    config = _schema_to_sample_configuration(schema)
+    source_config = None
+
+    if source_filename:
+        source_config = load.load_configuration(source_filename)
+
+    destination_config = merge_source_configuration_into_destination(
+        _schema_to_sample_configuration(schema), source_config
+    )
 
     write_configuration(
-        config_filename, _comment_out_optional_configuration(_render_configuration(config))
+        destination_filename,
+        _comment_out_optional_configuration(_render_configuration(destination_config)),
     )
diff --git a/docs/how-to/set-up-backups.md b/docs/how-to/set-up-backups.md
index f436041c2..bea044786 100644
--- a/docs/how-to/set-up-backups.md
+++ b/docs/how-to/set-up-backups.md
@@ -77,9 +77,12 @@ else borgmatic won't recognize the option. Also be sure to use spaces rather
 than tabs for indentation; YAML does not allow tabs.
 
 You can also get the same sample configuration file from the [configuration
-reference](https://torsion.org/borgmatic/docs/reference/configuration/), the authoritative set of
-all configuration options. This is handy if borgmatic has added new options
-since you originally created your configuration file.
+reference](https://torsion.org/borgmatic/docs/reference/configuration/), the
+authoritative set of all configuration options. This is handy if borgmatic has
+added new options
+since you originally created your configuration file. Also check out how to
+[upgrade your
+configuration](https://torsion.org/borgmatic/docs/how-to/upgrade/#upgrading-your-configuration).
 
 
 ### Encryption
@@ -248,5 +251,6 @@ it.
  * [Deal with very large backups](https://torsion.org/borgmatic/docs/how-to/deal-with-very-large-backups/)
  * [Inspect your backups](https://torsion.org/borgmatic/docs/how-to/inspect-your-backups/)
  * [Monitor your backups](https://torsion.org/borgmatic/docs/how-to/monitor-your-backups/)
+ * [Upgrade borgmatic](https://torsion.org/borgmatic/docs/how-to/upgrade/)
  * [borgmatic configuration reference](https://torsion.org/borgmatic/docs/reference/configuration/)
  * [borgmatic command-line reference](https://torsion.org/borgmatic/docs/reference/command-line/)
diff --git a/docs/how-to/upgrade.md b/docs/how-to/upgrade.md
index c66ebd47a..18455e8fb 100644
--- a/docs/how-to/upgrade.md
+++ b/docs/how-to/upgrade.md
@@ -10,7 +10,46 @@ following:
 sudo pip3 install --user --upgrade borgmatic
 ```
 
-See below about special cases.
+See below about special cases with old versions of borgmatic. Additionally, if
+you installed borgmatic [without using `pip3 install
+--user`](https://torsion.org/borgmatic/docs/how-to/set-up-backups/#other-ways-to-install),
+then your upgrade process may be different.
+
+
+### Upgrading your configuration
+
+The borgmatic configuration file format is almost always backwards-compatible
+from release to release without any changes, but you may still want to update
+your configuration file when you upgrade to take advantage of new
+configuration options. This is completely optional. If you prefer, you can add
+new configuration options manually.
+
+If you do want to upgrade your configuration file to include new options, use
+the `generate-borgmatic-config` script with its optional `--source` flag that
+takes the path to your original configuration file. If provided with this
+path, `generate-borgmatic-config` merges your original configuration into the
+generated configuration file, so you get all the newest options and comments.
+
+Here's an example:
+
+```bash
+generate-borgmatic-config --source config.yaml --destination config-new.yaml
+```
+
+New options start as commented out, so you can edit the file and decide
+whether you want to use each one.
+
+There are a few caveats to this process, however. First, when generating the
+new configuration file, `generate-borgmatic-config` replaces any comments
+you've written in your original configuration file with the newest generated
+comments. Second, the script adds back any options you had originally deleted,
+although it does so with the options commented out. And finally, any YAML
+includes you've used in the source configuration get flattened out into a
+single generated file.
+
+As a safety measure, `generate-borgmatic-config` refuses to modify
+configuration files in-place. So it's up to you to review the generated file
+and, if desired, replace your original configuration file with it.
 
 
 ### Upgrading from borgmatic 1.0.x
diff --git a/setup.py b/setup.py
index db3144bfb..53f894fbe 100644
--- a/setup.py
+++ b/setup.py
@@ -1,6 +1,6 @@
 from setuptools import find_packages, setup
 
-VERSION = '1.4.6'
+VERSION = '1.4.7'
 
 
 setup(
diff --git a/tests/integration/config/test_generate.py b/tests/integration/config/test_generate.py
index 7065a6022..0ff610f5c 100644
--- a/tests/integration/config/test_generate.py
+++ b/tests/integration/config/test_generate.py
@@ -47,9 +47,13 @@ def test_comment_out_line_comments_twice_indented_option():
 
 
 def test_comment_out_optional_configuration_comments_optional_config_only():
+    # The "# COMMENT_OUT" comment is a sentinel used to express that the following key is optional.
+    # It's stripped out of the final output.
     flexmock(module)._comment_out_line = lambda line: '# ' + line
     config = '''
+# COMMENT_OUT
 foo:
+    # COMMENT_OUT
     bar:
         - baz
         - quux
@@ -59,6 +63,8 @@ location:
         - one
         - two
 
+    # This comment should be kept.
+    # COMMENT_OUT
     other: thing
     '''
 
@@ -68,12 +74,13 @@ location:
 #     bar:
 #         - baz
 #         - quux
-# 
+
 location:
     repositories:
         - one
         - two
-# 
+
+    # This comment should be kept.
 #     other: thing
     '''
 
@@ -142,12 +149,67 @@ def test_add_comments_to_configuration_map_does_not_raise():
     module.add_comments_to_configuration_map(config, schema)
 
 
+def test_add_comments_to_configuration_map_with_skip_first_does_not_raise():
+    config = module.yaml.comments.CommentedMap([('foo', 33)])
+    schema = {'map': {'foo': {'desc': 'Foo'}}}
+
+    module.add_comments_to_configuration_map(config, schema, skip_first=True)
+
+
+def test_remove_commented_out_sentinel_keeps_other_comments():
+    field_name = 'foo'
+    config = module.yaml.comments.CommentedMap([(field_name, 33)])
+    config.yaml_set_comment_before_after_key(key=field_name, before='Actual comment.\nCOMMENT_OUT')
+
+    module.remove_commented_out_sentinel(config, field_name)
+
+    comments = config.ca.items[field_name][module.RUAMEL_YAML_COMMENTS_INDEX]
+    assert len(comments) == 1
+    assert comments[0].value == '# Actual comment.\n'
+
+
+def test_remove_commented_out_sentinel_without_sentinel_keeps_other_comments():
+    field_name = 'foo'
+    config = module.yaml.comments.CommentedMap([(field_name, 33)])
+    config.yaml_set_comment_before_after_key(key=field_name, before='Actual comment.')
+
+    module.remove_commented_out_sentinel(config, field_name)
+
+    comments = config.ca.items[field_name][module.RUAMEL_YAML_COMMENTS_INDEX]
+    assert len(comments) == 1
+    assert comments[0].value == '# Actual comment.\n'
+
+
+def test_remove_commented_out_sentinel_on_unknown_field_does_not_raise():
+    field_name = 'foo'
+    config = module.yaml.comments.CommentedMap([(field_name, 33)])
+    config.yaml_set_comment_before_after_key(key=field_name, before='Actual comment.')
+
+    module.remove_commented_out_sentinel(config, 'unknown')
+
+
 def test_generate_sample_configuration_does_not_raise():
     builtins = flexmock(sys.modules['builtins'])
     builtins.should_receive('open').with_args('schema.yaml').and_return('')
+    flexmock(module.yaml).should_receive('round_trip_load')
     flexmock(module).should_receive('_schema_to_sample_configuration')
+    flexmock(module).should_receive('merge_source_configuration_into_destination')
     flexmock(module).should_receive('_render_configuration')
     flexmock(module).should_receive('_comment_out_optional_configuration')
     flexmock(module).should_receive('write_configuration')
 
-    module.generate_sample_configuration('config.yaml', 'schema.yaml')
+    module.generate_sample_configuration(None, 'dest.yaml', 'schema.yaml')
+
+
+def test_generate_sample_configuration_with_source_filename_does_not_raise():
+    builtins = flexmock(sys.modules['builtins'])
+    builtins.should_receive('open').with_args('schema.yaml').and_return('')
+    flexmock(module.yaml).should_receive('round_trip_load')
+    flexmock(module.load).should_receive('load_configuration')
+    flexmock(module).should_receive('_schema_to_sample_configuration')
+    flexmock(module).should_receive('merge_source_configuration_into_destination')
+    flexmock(module).should_receive('_render_configuration')
+    flexmock(module).should_receive('_comment_out_optional_configuration')
+    flexmock(module).should_receive('write_configuration')
+
+    module.generate_sample_configuration('source.yaml', 'dest.yaml', 'schema.yaml')
diff --git a/tests/unit/config/test_convert.py b/tests/unit/config/test_convert.py
index cdf1d444c..8ae5dc678 100644
--- a/tests/unit/config/test_convert.py
+++ b/tests/unit/config/test_convert.py
@@ -21,6 +21,7 @@ def test_convert_section_generates_integer_value_for_integer_type_in_schema():
 
 def test_convert_legacy_parsed_config_transforms_source_config_to_mapping():
     flexmock(module.yaml.comments).should_receive('CommentedMap').replace_with(OrderedDict)
+    flexmock(module.generate).should_receive('add_comments_to_configuration_map')
     source_config = Parsed_config(
         location=OrderedDict([('source_directories', '/home'), ('repository', 'hostname.borg')]),
         storage=OrderedDict([('encryption_passphrase', 'supersecret')]),
@@ -53,6 +54,7 @@ def test_convert_legacy_parsed_config_transforms_source_config_to_mapping():
 
 def test_convert_legacy_parsed_config_splits_space_separated_values():
     flexmock(module.yaml.comments).should_receive('CommentedMap').replace_with(OrderedDict)
+    flexmock(module.generate).should_receive('add_comments_to_configuration_map')
     source_config = Parsed_config(
         location=OrderedDict(
             [('source_directories', '/home /etc'), ('repository', 'hostname.borg')]
diff --git a/tests/unit/config/test_generate.py b/tests/unit/config/test_generate.py
index aea5f1004..a0a79ba70 100644
--- a/tests/unit/config/test_generate.py
+++ b/tests/unit/config/test_generate.py
@@ -51,6 +51,7 @@ def test_schema_to_sample_configuration_generates_config_sequence_of_strings_wit
 def test_schema_to_sample_configuration_generates_config_sequence_of_maps_with_examples():
     flexmock(module.yaml.comments).should_receive('CommentedSeq').replace_with(list)
     flexmock(module).should_receive('add_comments_to_configuration_sequence')
+    flexmock(module).should_receive('add_comments_to_configuration_map')
     schema = {
         'seq': [
             {
@@ -71,3 +72,54 @@ def test_schema_to_sample_configuration_with_unsupported_schema_raises():
 
     with pytest.raises(ValueError):
         module._schema_to_sample_configuration(schema)
+
+
+def test_merge_source_configuration_into_destination_inserts_map_fields():
+    destination_config = {'foo': 'dest1', 'bar': 'dest2'}
+    source_config = {'foo': 'source1', 'baz': 'source2'}
+    flexmock(module).should_receive('remove_commented_out_sentinel')
+    flexmock(module).should_receive('yaml.comments.CommentedSeq').replace_with(list)
+
+    module.merge_source_configuration_into_destination(destination_config, source_config)
+
+    assert destination_config == {'foo': 'source1', 'bar': 'dest2', 'baz': 'source2'}
+
+
+def test_merge_source_configuration_into_destination_inserts_nested_map_fields():
+    destination_config = {'foo': {'first': 'dest1', 'second': 'dest2'}, 'bar': 'dest3'}
+    source_config = {'foo': {'first': 'source1'}}
+    flexmock(module).should_receive('remove_commented_out_sentinel')
+    flexmock(module).should_receive('yaml.comments.CommentedSeq').replace_with(list)
+
+    module.merge_source_configuration_into_destination(destination_config, source_config)
+
+    assert destination_config == {'foo': {'first': 'source1', 'second': 'dest2'}, 'bar': 'dest3'}
+
+
+def test_merge_source_configuration_into_destination_inserts_sequence_fields():
+    destination_config = {'foo': ['dest1', 'dest2'], 'bar': ['dest3'], 'baz': ['dest4']}
+    source_config = {'foo': ['source1'], 'bar': ['source2', 'source3']}
+    flexmock(module).should_receive('remove_commented_out_sentinel')
+    flexmock(module).should_receive('yaml.comments.CommentedSeq').replace_with(list)
+
+    module.merge_source_configuration_into_destination(destination_config, source_config)
+
+    assert destination_config == {
+        'foo': ['source1'],
+        'bar': ['source2', 'source3'],
+        'baz': ['dest4'],
+    }
+
+
+def test_merge_source_configuration_into_destination_inserts_sequence_of_maps():
+    destination_config = {'foo': [{'first': 'dest1', 'second': 'dest2'}], 'bar': 'dest3'}
+    source_config = {'foo': [{'first': 'source1'}, {'other': 'source2'}]}
+    flexmock(module).should_receive('remove_commented_out_sentinel')
+    flexmock(module).should_receive('yaml.comments.CommentedSeq').replace_with(list)
+
+    module.merge_source_configuration_into_destination(destination_config, source_config)
+
+    assert destination_config == {
+        'foo': [{'first': 'source1', 'second': 'dest2'}, {'other': 'source2'}],
+        'bar': 'dest3',
+    }