diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 6b53b11a58d5..5a9bab206602 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,30 +1,34 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2016-09-07 17:08:09 +0300 using RuboCop version 0.42.0.
+# on 2016-11-06 21:38:48 +0100 using RuboCop version 0.45.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 75
+# Offense count: 83
 Metrics/AbcSize:
   Max: 19
 
-# Offense count: 32
+# Offense count: 33
 # Configuration parameters: CountComments.
 Metrics/ClassLength:
   Max: 172
 
-# Offense count: 28
+# Offense count: 31
 Metrics/CyclomaticComplexity:
-  Max: 7
+  Max: 8
 
-# Offense count: 143
+# Offense count: 147
 # Configuration parameters: CountComments.
 Metrics/MethodLength:
   Max: 14
 
-# Offense count: 11
+# Offense count: 12
 # Configuration parameters: CountComments.
 Metrics/ModuleLength:
   Max: 156
+
+# Offense count: 1
+Metrics/PerceivedComplexity:
+  Max: 8
diff --git a/CHANGELOG.md b/CHANGELOG.md
index dfbef2f0ffa6..1e5073d4812f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
 * New cop `Rails/EnumUniqueness` checks for duplicate values defined in enum config hash. ([@olliebennett][])
 * [#3451](https://github.com/bbatsov/rubocop/issues/3451): Add new `require_parentheses_when_complex` style to `Style/TernaryParentheses` cop. ([@swcraig][])
 * [#3600](https://github.com/bbatsov/rubocop/issues/3600): Add new `Bundler/OrderedGems` cop. ([@tdeo][])
+* [#3479](https://github.com/bbatsov/rubocop/issues/3479): Add new configuration option `IgnoredPatterns` to `Metrics/LineLength`. ([@jonas054][])
 
 ### Changes
 
diff --git a/config/default.yml b/config/default.yml
index bcd07d09543b..df7ef621973f 100644
--- a/config/default.yml
+++ b/config/default.yml
@@ -1144,6 +1144,10 @@ Metrics/LineLength:
   # The IgnoreCopDirectives option causes the LineLength rule to ignore cop
   # directives like '# rubocop: enable ...' when calculating a line's length.
   IgnoreCopDirectives: false
+  # The IgnoredPatterns option is a list of !ruby/regexp and/or string
+  # elements. Strings will be converted to Regexp objects. A line that matches
+  # any regular expression listed in this option will be ignored by LineLength.
+  IgnoredPatterns: []
 
 Metrics/MethodLength:
   CountComments: false  # count full line comments?
diff --git a/lib/rubocop/cop/metrics/line_length.rb b/lib/rubocop/cop/metrics/line_length.rb
index f0d2f0cef9ea..064a6a32afb8 100644
--- a/lib/rubocop/cop/metrics/line_length.rb
+++ b/lib/rubocop/cop/metrics/line_length.rb
@@ -23,6 +23,7 @@ def investigate(processed_source)
 
         def check_line(line, index, heredocs)
           return if line.length <= max
+          return if matches_ignored_pattern?(line)
           if ignore_cop_directives? && directive_on_source_line?(index)
             return check_directive_line(line, index)
           end
@@ -81,6 +82,14 @@ def line_in_whitelisted_heredoc?(heredocs, line_number)
           end
         end
 
+        def matches_ignored_pattern?(line)
+          ignored_patterns.any? { |pattern| Regexp.new(pattern).match(line) }
+        end
+
+        def ignored_patterns
+          cop_config['IgnoredPatterns'] || []
+        end
+
         def allow_uri?
           cop_config['AllowURI']
         end
diff --git a/spec/rubocop/cli/cli_auto_gen_config_spec.rb b/spec/rubocop/cli/cli_auto_gen_config_spec.rb
index b5317cda0e71..34a2a355c55d 100644
--- a/spec/rubocop/cli/cli_auto_gen_config_spec.rb
+++ b/spec/rubocop/cli/cli_auto_gen_config_spec.rb
@@ -46,7 +46,7 @@ def abs(path)
       expect(IO.readlines('.rubocop_todo.yml')[8..-1].map(&:chomp))
         .to eq(['# Offense count: 1',
                 '# Configuration parameters: AllowHeredoc, AllowURI, ' \
-                'URISchemes, IgnoreCopDirectives.',
+                'URISchemes, IgnoreCopDirectives, IgnoredPatterns.',
                 '# URISchemes: http, https',
                 'Metrics/LineLength:',
                 '  Max: 85',
@@ -81,7 +81,7 @@ def abs(path)
       expect(IO.readlines('.rubocop_todo.yml')[8..-1].join)
         .to eq(['# Offense count: 1',
                 '# Configuration parameters: AllowHeredoc, AllowURI, ' \
-                'URISchemes, IgnoreCopDirectives.',
+                'URISchemes, IgnoreCopDirectives, IgnoredPatterns.',
                 '# URISchemes: http, https',
                 'Metrics/LineLength:',
                 '  Max: 81',
@@ -136,7 +136,7 @@ def abs(path)
          '',
          '# Offense count: 2',
          '# Configuration parameters: AllowHeredoc, AllowURI, URISchemes, '\
-         'IgnoreCopDirectives.',
+         'IgnoreCopDirectives, IgnoredPatterns.',
          '# URISchemes: http, https',
          'Metrics/LineLength:',
          '  Max: 90',
@@ -225,7 +225,7 @@ def abs(path)
          '',
          '# Offense count: 3',
          '# Configuration parameters: AllowHeredoc, AllowURI, URISchemes, '\
-         'IgnoreCopDirectives.',
+         'IgnoreCopDirectives, IgnoredPatterns.',
          '# URISchemes: http, https',
          'Metrics/LineLength:',
          '  Max: 90', # Offense occurs in 2 files, limit is 1, so no Exclude.
@@ -413,7 +413,7 @@ def abs(path)
          'again.',
          '',
          '# Configuration parameters: AllowHeredoc, AllowURI, URISchemes, '\
-         'IgnoreCopDirectives.',
+         'IgnoreCopDirectives, IgnoredPatterns.',
          '# URISchemes: http, https',
          'Metrics/LineLength:',
          '  Max: 90',
diff --git a/spec/rubocop/config_loader_spec.rb b/spec/rubocop/config_loader_spec.rb
index 19f0fc73b414..08301470c080 100644
--- a/spec/rubocop/config_loader_spec.rb
+++ b/spec/rubocop/config_loader_spec.rb
@@ -217,7 +217,8 @@
               'AllowHeredoc' => true,
               'AllowURI' => true,
               'URISchemes' => %w(http https),
-              'IgnoreCopDirectives' => false
+              'IgnoreCopDirectives' => false,
+              'IgnoredPatterns' => []
             },
             'Metrics/MethodLength' => {
               'Description' =>
@@ -297,7 +298,8 @@
               'AllowHeredoc' => false,  # overridden in rubocop.yml
               'AllowURI' => true,
               'URISchemes' => %w(http https),
-              'IgnoreCopDirectives' => false
+              'IgnoreCopDirectives' => false,
+              'IgnoredPatterns' => []
             }
           )
 
diff --git a/spec/rubocop/cop/metrics/line_length_spec.rb b/spec/rubocop/cop/metrics/line_length_spec.rb
index 300c331dbe67..7d038cb064a9 100644
--- a/spec/rubocop/cop/metrics/line_length_spec.rb
+++ b/spec/rubocop/cop/metrics/line_length_spec.rb
@@ -4,7 +4,7 @@
 
 describe RuboCop::Cop::Metrics::LineLength, :config do
   subject(:cop) { described_class.new(config) }
-  let(:cop_config) { { 'Max' => 80 } }
+  let(:cop_config) { { 'Max' => 80, 'IgnoredPatterns' => nil } }
 
   it "registers an offense for a line that's 81 characters wide" do
     inspect_source(cop, '#' * 81)
@@ -118,6 +118,29 @@
     end
   end
 
+  context 'when IgnoredPatterns option is set' do
+    let(:cop_config) do
+      {
+        'Max' => 18,
+        'IgnoredPatterns' => ['^\s*test\s', /^\s*def\s+test_/]
+      }
+    end
+
+    let(:source) do
+      ['class ExampleTest < TestCase',
+       "  test 'some really long test description which exceeds length' do",
+       '  end',
+       '  def test_some_other_long_test_description_which_exceeds_length',
+       '  end',
+       'end']
+    end
+
+    it 'accepts long lines matching a pattern but not other long lines' do
+      inspect_source(cop, source)
+      expect(cop.highlights).to eq(['< TestCase'])
+    end
+  end
+
   context 'when AllowHeredoc option is enabled' do
     let(:cop_config) { { 'Max' => 80, 'AllowHeredoc' => true } }
 
@@ -142,7 +165,7 @@
 
     context 'and only certain heredoc delimiters are whitelisted' do
       let(:cop_config) do
-        { 'Max' => 80, 'AllowHeredoc' => %w(SQL OK) }
+        { 'Max' => 80, 'AllowHeredoc' => %w(SQL OK), 'IgnoredPatterns' => [] }
       end
 
       let(:source) { <<-END }