diff --git a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder-side-by-side.js b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder-side-by-side.js
index 126882c..23c5036 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder-side-by-side.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder-side-by-side.js
@@ -34,6 +34,29 @@
     return sectionEl;
   };
 
+  GrDiffBuilderSideBySide.prototype.addColumns = function(outputEl, fontSize) {
+    var width = fontSize * 4;
+    var colgroup = document.createElement('colgroup');
+
+    // Add left-side line number.
+    var col = document.createElement('col');
+    col.setAttribute('width', width);
+    colgroup.appendChild(col);
+
+    // Add left-side content.
+    colgroup.appendChild(document.createElement('col'));
+
+    // Add right-side line number.
+    col = document.createElement('col');
+    col.setAttribute('width', width);
+    colgroup.appendChild(col);
+
+    // Add right-side content.
+    colgroup.appendChild(document.createElement('col'));
+
+    outputEl.appendChild(colgroup);
+  };
+
   GrDiffBuilderSideBySide.prototype._createRow = function(section, leftLine,
       rightLine) {
     var row = this._createElement('tr');
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder-unified.js b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder-unified.js
index e1f3ed1..d2c543d 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder-unified.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder-unified.js
@@ -33,6 +33,26 @@
     return sectionEl;
   };
 
+  GrDiffBuilderUnified.prototype.addColumns = function(outputEl, fontSize) {
+    var width = fontSize * 4;
+    var colgroup = document.createElement('colgroup');
+
+    // Add left-side line number.
+    var col = document.createElement('col');
+    col.setAttribute('width', width);
+    colgroup.appendChild(col);
+
+    // Add right-side line number.
+    col = document.createElement('col');
+    col.setAttribute('width', width);
+    colgroup.appendChild(col);
+
+    // Add the content.
+    colgroup.appendChild(document.createElement('col'));
+
+    outputEl.appendChild(colgroup);
+  };
+
   GrDiffBuilderUnified.prototype._createRow = function(section, line) {
     var row = this._createElement('tr', line.type);
     var lineEl = this._createLineEl(line, line.beforeNumber,
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder.html b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder.html
index 0a595c7..c944db4 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder.html
@@ -126,6 +126,7 @@
           this.$.processor.keyLocations = this._getCommentLocations(comments);
 
           this._clearDiffContent();
+          this._builder.addColumns(this.diffElement, prefs.font_size);
 
           var reporting = this.$.reporting;
 
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder.js b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder.js
index c524f7f..d987972 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder.js
@@ -65,7 +65,20 @@
 
   var PARTIAL_CONTEXT_AMOUNT = 10;
 
-  GrDiffBuilder.prototype.buildSectionElement = function(group) {
+  /**
+   * Abstract method
+   * @param {string} outputEl
+   * @param {number} fontSize
+   */
+  GrDiffBuilder.prototype.addColumns = function() {
+    throw Error('Subclasses must implement addColumns');
+  };
+
+  /**
+   * Abstract method
+   * @param {Object} group
+   */
+  GrDiffBuilder.prototype.buildSectionElement = function() {
     throw Error('Subclasses must implement buildGroupElement');
   };
 
@@ -377,7 +390,8 @@
     var html = util.escapeHTML(text);
     html = this._addTabWrappers(html, this._prefs.tab_size);
 
-    if (this._textLength(text, this._prefs.tab_size) >
+    if (!this._prefs.line_wrapping &&
+        this._textLength(text, this._prefs.tab_size) >
         this._prefs.line_length) {
       html = this._addNewlines(text, html);
     }
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder_test.html b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder_test.html
index 69fea31..ad5173d 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder_test.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-builder/gr-diff-builder_test.html
@@ -124,6 +124,36 @@
           '6789');
     });
 
+    test('_addNewlines not called if line_wrapping is true', function(done) {
+      builder._prefs = {line_wrapping: true, tab_size: 4, line_length: 50};
+      var text = (new Array(52)).join('a');
+
+      var line = {text: text, highlights: []};
+      var newLineStub = sinon.stub(builder, '_addNewlines');
+      builder._createTextEl(line);
+      flush(function() {
+        assert.isFalse(newLineStub.called);
+        newLineStub.restore();
+        done();
+      });
+    });
+
+    test('_addNewlines called if line_wrapping is true and meets other ' +
+        'conditions', function(done) {
+      builder._prefs = {line_wrapping: false, tab_size: 4, line_length: 50};
+      var text = (new Array(52)).join('a');
+
+      var line = {text: text, highlights: []};
+      var newLineStub = sinon.stub(builder, '_addNewlines');
+      builder._createTextEl(line);
+
+      flush(function() {
+        assert.isTrue(newLineStub.called);
+        newLineStub.restore();
+        done();
+      });
+    });
+
     test('text length with tabs and unicode', function() {
       assert.equal(builder._textLength('12345', 4), 5);
       assert.equal(builder._textLength('\t\t12', 4), 10);
@@ -531,8 +561,10 @@
     suite('rendering', function() {
       var content;
       var outputEl;
+      var sandbox;
 
       setup(function(done) {
+        sandbox = sinon.sandbox.create();
         var prefs = {
           line_length: 10,
           show_tabs: true,
@@ -553,19 +585,15 @@
           },
         ];
         stub('gr-reporting', {
-          time: sinon.stub(),
-          timeEnd: sinon.stub(),
+          time: sandbox.stub(),
+          timeEnd: sandbox.stub(),
         });
         element = fixture('basic');
         outputEl = element.queryEffectiveChildren('#diffTable');
-        var renderHandler = function() {
-          element.removeEventListener('render', renderHandler);
-          done();
-        };
-        element.addEventListener('render', renderHandler);
-        sinon.stub(element, '_getDiffBuilder', function() {
+        sandbox.stub(element, '_getDiffBuilder', function() {
           var builder = new GrDiffBuilder(
               {content: content}, {left: [], right: []}, prefs, outputEl);
+          sandbox.stub(builder, 'addColumns');
           builder.buildSectionElement = function(group) {
             var section = document.createElement('stub');
             section.textContent = group.lines.reduce(function(acc, line) {
@@ -576,21 +604,23 @@
           return builder;
         });
         element.diff = {content: content};
-        element.render({left: [], right: []}, prefs);
+        element.render({left: [], right: []}, prefs).then(done);
+      });
+
+      teardown(function() {
+        sandbox.restore();
       });
 
       test('reporting', function(done) {
         var timeStub = element.$.reporting.time;
         var timeEndStub = element.$.reporting.timeEnd;
-        flush(function() {
-          assert.isTrue(timeStub.calledWithExactly('Diff Total Render'));
-          assert.isTrue(timeStub.calledWithExactly('Diff Content Render'));
-          assert.isTrue(timeStub.calledWithExactly('Diff Syntax Render'));
-          assert.isTrue(timeEndStub.calledWithExactly('Diff Total Render'));
-          assert.isTrue(timeEndStub.calledWithExactly('Diff Content Render'));
-          assert.isTrue(timeEndStub.calledWithExactly('Diff Syntax Render'));
-          done();
-        });
+        assert.isTrue(timeStub.calledWithExactly('Diff Total Render'));
+        assert.isTrue(timeStub.calledWithExactly('Diff Content Render'));
+        assert.isTrue(timeStub.calledWithExactly('Diff Syntax Render'));
+        assert.isTrue(timeEndStub.calledWithExactly('Diff Total Render'));
+        assert.isTrue(timeEndStub.calledWithExactly('Diff Content Render'));
+        assert.isTrue(timeEndStub.calledWithExactly('Diff Syntax Render'));
+        done();
       });
 
       test('renderSection', function() {
@@ -602,6 +632,11 @@
         assert.equal(section.innerHTML, prevInnerHTML);
       });
 
+      test('addColumns is called', function(done) {
+        element.render({left: [], right: []}, {}).then(done);
+        assert.isTrue(element._builder.addColumns.called);
+      });
+
       test('getSectionsByLineRange one line', function() {
         var section = outputEl.querySelector('stub:nth-of-type(2)');
         var sections = element._builder.getSectionsByLineRange(1, 1, 'left');
@@ -622,8 +657,7 @@
 
       test('render-start and render are fired', function(done) {
         var fireStub = sinon.stub(element, 'fire');
-        element.render({left: [], right: []}, {});
-        flush(function() {
+        element.render({left: [], right: []}, {}).then(function() {
           assert.isTrue(fireStub.calledWithExactly('render-start'));
           assert.isTrue(fireStub.calledWithExactly('render'));
           done();
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.html b/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.html
index 4e64dcd..1188dd3 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.html
@@ -87,7 +87,15 @@
         </select>
       </div>
       <div class="pref">
-        <label for="columnsInput">Columns</label>
+        <label for="lineWrappingInput">Fit to Screen</label>
+        <input
+            is="iron-input"
+            type="checkbox"
+            id="lineWrappingInput"
+            on-tap="_handlelineWrappingTap">
+      </div>
+      <div class="pref" id="columnsPref" hidden$="[[_newPrefs.line_wrapping]]">
+        <label for="columnsInput">Diff Width</label>
         <input is="iron-input" type="number" id="columnsInput"
             prevent-invalid-input
             allowed-pattern="[0-9]"
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.js b/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.js
index 9bccd23..2d6bd8c 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences.js
@@ -72,6 +72,7 @@
       this._newPrefs = Object.assign({}, prefs);
       this.$.contextSelect.value = prefs.context;
       this.$.showTabsInput.checked = prefs.show_tabs;
+      this.$.lineWrappingInput.checked = prefs.line_wrapping;
       this.$.syntaxHighlightInput.checked = prefs.syntax_highlighting;
     },
 
@@ -95,6 +96,10 @@
           Polymer.dom(e).rootTarget.checked);
     },
 
+    _handlelineWrappingTap: function(e) {
+      this.set('_newPrefs.line_wrapping', Polymer.dom(e).rootTarget.checked);
+    },
+
     _handleSave: function() {
       this.prefs = this._newPrefs;
       this.localPrefs = this._newLocalPrefs;
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences_test.html b/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences_test.html
index c595663..9ec8a02 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences_test.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-preferences/gr-diff-preferences_test.html
@@ -56,15 +56,29 @@
       element.$.tabSizeInput.bindValue = 4;
       MockInteractions.tap(element.$.showTabsInput);
       MockInteractions.tap(element.$.syntaxHighlightInput);
+      MockInteractions.tap(element.$.lineWrappingInput);
 
       assert.equal(element._newPrefs.context, 50);
       assert.equal(element._newPrefs.font_size, 10);
       assert.equal(element._newPrefs.line_length, 80);
       assert.equal(element._newPrefs.tab_size, 4);
       assert.isFalse(element._newPrefs.show_tabs);
+      assert.isTrue(element._newPrefs.line_wrapping);
       assert.isFalse(element._newPrefs.syntax_highlighting);
     });
 
+    test('clicking fit to screen hides line length input', function() {
+      element.prefs = {line_wrapping: false};
+
+      assert.isFalse(element.$.columnsPref.hidden);
+
+      MockInteractions.tap(element.$.lineWrappingInput);
+      assert.isTrue(element.$.columnsPref.hidden);
+
+      MockInteractions.tap(element.$.lineWrappingInput);
+      assert.isFalse(element.$.columnsPref.hidden);
+    });
+
     test('clicking save button calls _handleSave function', function() {
       var savePrefs = sinon.stub(element, '_handleSave');
       MockInteractions.tap(element.$.saveButton);
diff --git a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
index 14c2bb5..0816501 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.html
@@ -87,8 +87,13 @@
       .content {
         background-color: #fff;
       }
+      .full-width {
+        width: 100%;
+      }
       .lineNum,
       .content {
+        /* Set font size based the user's diff preference. */
+        font-size: var(--font-size, 12px);
         vertical-align: top;
         white-space: pre;
       }
@@ -113,11 +118,7 @@
            allows them to shrink. */
         max-width: var(--content-width, 80ch);
         min-width: var(--content-width, 80ch);
-      }
-      .content,
-      .lineNum {
-        /* Set font size based the user's diff preference. */
-        font-size: var(--font-size, 12px);
+        width: var(--content-width, 80ch);
       }
       .content.add .intraline,
       .content.add.darkHighlight {
@@ -137,6 +138,10 @@
         background-color: #fef;
         color: #849;
       }
+      .contentText {
+        white-space: pre-wrap;
+        word-wrap: break-word;
+      }
       .contextControl gr-button {
         display: inline-block;
         font-family: var(--monospace-font-family);
@@ -171,10 +176,11 @@
               comments="[[_comments]]"
               diff="[[_diff]]"
               view-mode="[[viewMode]]"
+              line-wrapping="[[lineWrapping]]"
               is-image-diff="[[isImageDiff]]"
               base-image="[[_baseImage]]"
               revision-image="[[_revisionImage]]">
-            <table id="diffTable"></table>
+            <table id="diffTable" class$="[[_diffTableClass]]"></table>
           </gr-diff-builder>
         </gr-diff-highlight>
       </gr-diff-selection>
diff --git a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.js b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.js
index d3d78c4..eb95a77 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff/gr-diff.js
@@ -66,12 +66,21 @@
         type: Boolean,
         value: false,
       },
+      lineWrapping: {
+        type: Boolean,
+        value: false,
+        observer: '_lineWrappingObserver',
+      },
       viewMode: {
         type: String,
         value: DiffViewMode.SIDE_BY_SIDE,
         observer: '_viewModeObserver',
       },
       _diff: Object,
+      _diffTableClass: {
+        type: String,
+        value: '',
+      },
       _comments: Object,
       _baseImage: Object,
       _revisionImage: Object,
@@ -356,9 +365,21 @@
       this._prefsChanged(this.prefs);
     },
 
+    _lineWrappingObserver: function() {
+      this._prefsChanged(this.prefs);
+    },
+
     _prefsChanged: function(prefs) {
       if (!prefs) { return; }
-      this.customStyle['--content-width'] = prefs.line_length + 'ch';
+      if (prefs.line_wrapping) {
+        this._diffTableClass = 'full-width';
+        if (this.viewMode === 'SIDE_BY_SIDE') {
+          this.customStyle['--content-width'] = 'none';
+        }
+      } else {
+        this._diffTableClass = '';
+        this.customStyle['--content-width'] = prefs.line_length + 'ch';
+      }
 
       if (!!prefs.font_size) {
         this.customStyle['--font-size'] = prefs.font_size + 'px';