diff --git a/common/changes/office-ui-fabric-react/BaseButton_ContextMenu_AriaLabelledBy_2018-05-23-16-36.json b/common/changes/office-ui-fabric-react/BaseButton_ContextMenu_AriaLabelledBy_2018-05-23-16-36.json
new file mode 100644
index 00000000000000..92c58af4905aca
--- /dev/null
+++ b/common/changes/office-ui-fabric-react/BaseButton_ContextMenu_AriaLabelledBy_2018-05-23-16-36.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "office-ui-fabric-react",
+      "comment": "BaseButton sometimes has aria-labelledBy pointing to element that isn't in the DOM",
+      "type": "patch"
+    }
+  ],
+  "packageName": "office-ui-fabric-react",
+  "email": "rpsenski@microsoft.com"
+}
\ No newline at end of file
diff --git a/packages/office-ui-fabric-react/src/components/Button/BaseButton.tsx b/packages/office-ui-fabric-react/src/components/Button/BaseButton.tsx
index 01af263a9b64e8..fe9d56983bb5e7 100644
--- a/packages/office-ui-fabric-react/src/components/Button/BaseButton.tsx
+++ b/packages/office-ui-fabric-react/src/components/Button/BaseButton.tsx
@@ -347,7 +347,7 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
       text = children;
     }
 
-    if (text) {
+    if (this._hasText()) {
       return (
         <div
           key={ this._labelId }
@@ -362,6 +362,13 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
     return null;
   }
 
+  private _hasText(): boolean {
+    // _onRenderTextContents and _onRenderText do not perform the same checks. Below is parity with what _onRenderText used to have
+    // before the refactor that introduced this function. _onRenderTextContents does not require props.text to be undefined in order
+    // for props.children to be used as a fallback. Purely a code maintainability/reuse issue, but logged as Issue #4979
+    return this.props.text !== null && (this.props.text !== undefined || typeof (this.props.children) === 'string');
+  }
+
   private _onRenderChildren = (): JSX.Element | null => {
     const { children } = this.props;
 
@@ -427,6 +434,13 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
   private _onRenderMenu = (menuProps: IContextualMenuProps): JSX.Element => {
     const { onDismiss = this._dismissMenu } = menuProps;
 
+    // the accessible menu label (accessible name) has a relationship to the button.
+    // If the menu props do not specify an explicit value for aria-label or aria-labelledBy,
+    // AND the button has text, we'll set the menu aria-labelledBy to the text element id.
+    if (!menuProps.ariaLabel && !menuProps.labelElementId && this._hasText()) {
+      menuProps = { ...menuProps, labelElementId: this._labelId };
+    }
+
     return (
       <ContextualMenu
         id={ this._labelId + '-menu' }
@@ -435,7 +449,6 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
         shouldFocusOnContainer={ this.state.menuProps ? this.state.menuProps.shouldFocusOnContainer : undefined }
         className={ css('ms-BaseButton-menuhost', menuProps.className) }
         target={ this._isSplitButton ? this._splitButtonContainer.current : this._buttonElement.current }
-        labelElementId={ this._labelId }
         onDismiss={ onDismiss }
       />
     );
diff --git a/packages/office-ui-fabric-react/src/components/Button/Button.test.tsx b/packages/office-ui-fabric-react/src/components/Button/Button.test.tsx
index 205cf98bc14388..0688542992bedf 100644
--- a/packages/office-ui-fabric-react/src/components/Button/Button.test.tsx
+++ b/packages/office-ui-fabric-react/src/components/Button/Button.test.tsx
@@ -459,7 +459,7 @@ describe('Button', () => {
       expect(menuButtonDOM.getAttribute('aria-expanded')).toEqual('false');
     });
 
-    it('If menu trigger is specefied, default key is overridden', () => {
+    it('If menu trigger is specified, default key is overridden', () => {
       const button = ReactTestUtils.renderIntoDocument<any>(
         <DefaultButton
           data-automation-id='test'
@@ -637,5 +637,77 @@ describe('Button', () => {
         expect(didClick).toEqual(false);
       });
     });
+
+    describe('with contextual menu', () => {
+      function buildRenderAndClickButtonAndReturnContextualMenuDOMElement(menuPropsPatch?: any, text?: string, textAsChildElement: boolean = false): HTMLElement {
+        const menuProps = { items: [{ key: 'item', name: 'Item' }], ...menuPropsPatch };
+        const element: React.ReactElement<any> = (
+          <DefaultButton
+            iconProps={ { iconName: 'Add' } }
+            text={ !textAsChildElement && text ? text : undefined }
+            menuProps={ ...menuProps }
+          >
+            { textAsChildElement && text ? text : null }
+          </DefaultButton>
+        );
+
+        const button = ReactTestUtils.renderIntoDocument<any>(element) as React.ReactInstance;
+        const renderedDOM = ReactDOM.findDOMNode(button) as HTMLElement;
+
+        expect(renderedDOM).toBeDefined();
+        ReactTestUtils.Simulate.click(renderedDOM);
+
+        // get the menu id from the button's aria attribute
+        const menuId = renderedDOM.getAttribute('aria-owns');
+        expect(menuId).toBeDefined();
+
+        const menuDOM = renderedDOM.ownerDocument.getElementById(menuId as string);
+        expect(menuDOM).toBeDefined();
+
+        return menuDOM as HTMLElement;
+      }
+
+      it('If button has text, contextual menu has aria-labelledBy attribute set', () => {
+        const contextualMenuElement = buildRenderAndClickButtonAndReturnContextualMenuDOMElement(null, 'Button Text');
+
+        expect(contextualMenuElement).not.toBeNull();
+        expect(contextualMenuElement.getAttribute('aria-label') === null);
+        expect(contextualMenuElement.getAttribute('aria-labelledBy') !== null);
+      });
+
+      it('If button has a text child, contextual menu has aria-labelledBy attribute set', () => {
+        const contextualMenuElement = buildRenderAndClickButtonAndReturnContextualMenuDOMElement(null, 'Button Text', true);
+
+        expect(contextualMenuElement).not.toBeNull();
+        expect(contextualMenuElement.getAttribute('aria-label') === null);
+        expect(contextualMenuElement.getAttribute('aria-labelledBy') !== null);
+      });
+
+      it('If button has no text, contextual menu has no aria-label or aria-labelledBy attributes', () => {
+        const contextualMenuElement = buildRenderAndClickButtonAndReturnContextualMenuDOMElement();
+
+        expect(contextualMenuElement).not.toBeNull();
+        expect(contextualMenuElement.getAttribute('aria-label') === null);
+        expect(contextualMenuElement.getAttribute('aria-labelledBy') === null);
+      });
+
+      it('If button has text but ariaLabel provided in menuProps, contextual menu has aria-label set', () => {
+        const explicitLabel = 'ExplicitLabel';
+        const contextualMenuElement = buildRenderAndClickButtonAndReturnContextualMenuDOMElement({ ariaLabel: explicitLabel }, 'Button Text');
+
+        expect(contextualMenuElement).not.toBeNull();
+        expect(contextualMenuElement.getAttribute('aria-label') === explicitLabel);
+        expect(contextualMenuElement.getAttribute('aria-labelledBy') === null);
+      });
+
+      it('If button has text but labelElementId provided in menuProps, contextual menu has aria-labelledBy reflecting labelElementId', () => {
+        const explicitLabelElementId = 'id_ExplicitLabel';
+        const contextualMenuElement = buildRenderAndClickButtonAndReturnContextualMenuDOMElement({ labelElementId: explicitLabelElementId }, 'Button Text');
+
+        expect(contextualMenuElement).not.toBeNull();
+        expect(contextualMenuElement.getAttribute('aria-label') === null);
+        expect(contextualMenuElement.getAttribute('aria-labelledBy') === explicitLabelElementId);
+      });
+    });
   });
 });