diff --git a/flake8/checker.py b/flake8/checker.py
index a6c14ecb..82f9e796 100644
--- a/flake8/checker.py
+++ b/flake8/checker.py
@@ -17,6 +17,9 @@
 
 LOG = logging.getLogger(__name__)
 
+SKIP_TOKENS = frozenset([tokenize.NL, tokenize.NEWLINE, tokenize.INDENT,
+                         tokenize.DEDENT])
+
 
 class Manager(object):
     """Manage the parallelism and checker instances for each plugin and file.
@@ -216,8 +219,15 @@ def run_check(self, plugin, **arguments):
 
     def run_logical_checks(self):
         """Run all checks expecting a logical line."""
+        comments, logical_line, mapping = self.processor.build_logical_line()
+        if not mapping:
+            return
+        self.processor.update_state(mapping)
+
+        LOG.debug('Logical line: "%s"', logical_line.rstrip())
+
         for plugin in self.checks.logical_line_plugins:
-            result = self.run_check(plugin)  # , logical_line=logical_line)
+            result = self.run_check(plugin, logical_line=logical_line)
             if result is not None:
                 column_offset, text = result
                 self.report(
@@ -415,6 +425,45 @@ def visited_new_blank_line(self):
         """Note that we visited a new blank line."""
         self.blank_lines += 1
 
+    def build_logical_line_tokens(self):
+        """Build the mapping, comments, and logical line lists."""
+        logical = []
+        comments = []
+        length = 0
+        previous_row = previous_column = mapping = None
+        for token_type, text, start, end, line in self.tokens:
+            if token_type in SKIP_TOKENS:
+                continue
+            if not mapping:
+                mapping = [(0, start)]
+            if token_type == tokenize.COMMENT:
+                comments.append(text)
+                continue
+            if token_type == tokenize.STRING:
+                text = utils.mutate_string(text)
+            if previous_row:
+                (start_row, start_column) = start
+                if previous_row != start_row:
+                    row_index = previous_row - 1
+                    column_index = previous_column - 1
+                    previous_text = self.lines[row_index][column_index]
+                    if (previous_text == ',' or
+                            (previous_text not in '{[(' and
+                             text not in '}])')):
+                        text = ' ' + text
+                    elif previous_column != start_column:
+                        text = line[previous_column:start_column] + text
+            logical.append(text)
+            length += len(text)
+            mapping.append((length, end))
+            (previous_row, previous_column) = end
+        return comments, logical, mapping
+
+    def build_logical_line(self):
+        """Build a logical line from the current tokens list."""
+        comments, logical, mapping_list = self.build_logical_line_tokens()
+        return ''.join(comments), ''.join(logical), mapping_list
+
     def split_line(self, token):
         """Split a physical line's line based on new-lines.
 
diff --git a/flake8/utils.py b/flake8/utils.py
index 97b766af..fe024d1f 100644
--- a/flake8/utils.py
+++ b/flake8/utils.py
@@ -223,3 +223,23 @@ def count_parentheses(current_parentheses_count, token_text):
         return current_parentheses_count + 1
     elif token_text in '}])':
         return current_parentheses_count - 1
+
+
+def mutate_string(text):
+    """Replace contents with 'xxx' to prevent syntax matching.
+
+    >>> mute_string('"abc"')
+    '"xxx"'
+    >>> mute_string("'''abc'''")
+    "'''xxx'''"
+    >>> mute_string("r'abc'")
+    "r'xxx'"
+    """
+    # String modifiers (e.g. u or r)
+    start = text.index(text[-1]) + 1
+    end = len(text) - 1
+    # Triple quotes
+    if text[-3:] in ('"""', "'''"):
+        start += 2
+        end -= 2
+    return text[:start] + 'x' * (end - start) + text[end:]