diff --git a/core/creators/themedui.js b/core/creators/themedui.js
index 4df16f428b2..26989019620 100644
--- a/core/creators/themedui.js
+++ b/core/creators/themedui.js
@@ -260,7 +260,7 @@ CKEDITOR.replaceClass = 'ckeditor';
 	 * ```
 	 *
 	 * @param {Number/String} width The new width. It can be an integer denoting a value
-	 * in pixels or a CSS size value with unit.
+	 * in pixels or a CSS size value with unit. When null is passed, the value will not be set.
 	 * @param {Number/String} height The new height. It can be an integer denoting a value
 	 * in pixels or a CSS size value with unit.
 	 * @param {Boolean} [isContentHeight] Indicates that the provided height is to
diff --git a/plugins/autogrow/plugin.js b/plugins/autogrow/plugin.js
index f9538b6b41f..25b14150f56 100644
--- a/plugins/autogrow/plugin.js
+++ b/plugins/autogrow/plugin.js
@@ -148,11 +148,8 @@
 			if ( newHeight != currentHeight && lastHeight != newHeight ) {
 				newHeight = editor.fire( 'autoGrow', { currentHeight: currentHeight, newHeight: newHeight } ).newHeight;
 
-				var boxSizingType = editor.container.getComputedStyle( 'box-sizing' ),
-					isBorderBox = boxSizingType === 'border-box',
-					width = editor.container.getSize( 'width', isBorderBox );
-
-				editor.resize( width, newHeight, true );
+				// Set width parameter as null, to update only the height of the editor. (#4891)
+				editor.resize( null, newHeight, true );
 				lastHeight = newHeight;
 			}
 
diff --git a/tests/plugins/autogrow/autogrow.js b/tests/plugins/autogrow/autogrow.js
index 58b33298366..c8e97ca46d8 100644
--- a/tests/plugins/autogrow/autogrow.js
+++ b/tests/plugins/autogrow/autogrow.js
@@ -56,6 +56,25 @@
 
 				editor.execCommand( 'autogrow' );
 
+				wait();
+			} );
+		},
+
+		// (#4891)
+		'test autogrow shouldn\'t add inline width property to editor container': function() {
+			var editor = this.editor,
+				bot = this.editorBot;
+
+			bot.setData( autogrowTools.getTestContent( 10 ), function() {
+				editor.once( 'afterCommandExec', function() {
+					resume( function() {
+						var editorContainerInlineWidth = editor.container.getStyle( 'width' );
+
+						assert.areSame( editorContainerInlineWidth, '', 'Editor shouldn\'t have any inline width property' );
+					} );
+				} );
+
+				editor.execCommand( 'autogrow' );
 				wait();
 			} );
 		}