diff --git a/Libraries/StyleSheet/__tests__/normalizeColor-test.js b/Libraries/StyleSheet/__tests__/normalizeColor-test.js
index dc12de12ff4fa4..fd8d7d14746093 100644
--- a/Libraries/StyleSheet/__tests__/normalizeColor-test.js
+++ b/Libraries/StyleSheet/__tests__/normalizeColor-test.js
@@ -123,4 +123,9 @@ describe('normalizeColor', function() {
     expect(normalizeColor(0xffffffff)).toBe(0xffffffff);
     expect(normalizeColor(0x01234567)).toBe(0x01234567);
   });
+
+  it('should return the same color when it\'s already normalized', function() {
+    const normalizedColor = normalizeColor('red') || 0;
+    expect(normalizeColor(normalizedColor)).toBe(normalizedColor);
+  });
 });
diff --git a/Libraries/StyleSheet/__tests__/setNormalizedColorAlpha-test.js b/Libraries/StyleSheet/__tests__/setNormalizedColorAlpha-test.js
new file mode 100644
index 00000000000000..598652dbba7b35
--- /dev/null
+++ b/Libraries/StyleSheet/__tests__/setNormalizedColorAlpha-test.js
@@ -0,0 +1,36 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+jest.dontMock('setNormalizedColorAlpha');
+jest.dontMock('normalizeColor');
+
+var setNormalizedColorAlpha = require('setNormalizedColorAlpha');
+var normalizeColor = require('normalizeColor');
+
+describe('setNormalizedColorAlpha', function() {
+  it('should adjust the alpha of the color passed in', function() {
+    expect(setNormalizedColorAlpha(0xffffffff, 0.4)).toBe(0xffffff66);
+    expect(setNormalizedColorAlpha(0x204080ff, 0.6)).toBe(0x20408099);
+  });
+
+  it('should clamp invalid input', function() {
+    expect(setNormalizedColorAlpha(0xffffffff, 1.5)).toBe(0xffffffff);
+    expect(setNormalizedColorAlpha(0xffffffff, -1)).toBe(0xffffff00);
+  });
+
+  it('should ignore the color\'s original alpha', function() {
+    expect(setNormalizedColorAlpha(0x204080aa, 0.8)).toBe(0x204080cc);
+  });
+
+  it('should return the original color when alpha is unchanged', function() {
+    var originalColor = normalizeColor('blue');
+    expect(setNormalizedColorAlpha(originalColor, 1)).toBe(originalColor);
+  });
+});
diff --git a/Libraries/StyleSheet/setNormalizedColorAlpha.js b/Libraries/StyleSheet/setNormalizedColorAlpha.js
new file mode 100644
index 00000000000000..cd943309922c0e
--- /dev/null
+++ b/Libraries/StyleSheet/setNormalizedColorAlpha.js
@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule setNormalizedColorAlpha
+ * @flow
+ */
+/* eslint no-bitwise: 0 */
+'use strict';
+
+/**
+ * number should be a color processed by `normalizeColor`
+ * alpha should be number between 0 and 1
+ */
+function setNormalizedColorAlpha(input: number, alpha: number): number {
+  if (alpha < 0) {
+    alpha = 0;
+  } else if (alpha > 1) {
+    alpha = 1;
+  }
+
+  alpha = Math.round(alpha * 255);
+  // magic bitshift guarantees we return an unsigned int
+  return ((input & 0xffffff00) | alpha) >>> 0;
+}
+
+module.exports = setNormalizedColorAlpha;