diff -r 3b4d00e20694 Doc/library/stdtypes.rst
--- a/Doc/library/stdtypes.rst	Mon Dec 19 22:05:46 2016 +0800
+++ b/Doc/library/stdtypes.rst	Mon Dec 19 09:56:38 2016 -0600
@@ -2314,11 +2314,14 @@
 
    This :class:`bytes` class method returns a bytes object, decoding the
    given string object.  The string must contain two hexadecimal digits per
-   byte, with ASCII spaces being ignored.
+   byte, with ASCII whitespace being ignored.
 
    >>> bytes.fromhex('2Ef0 F1f2  ')
    b'.\xf0\xf1\xf2'
 
+   .. versionchanged:: 3.7
+      :meth:`bytes.fromhex` now skips all ASCII whitespace in the string, not just spaces.
+
 A reverse conversion function exists to transform a bytes object into its
 hexadecimal representation.
 
@@ -2382,11 +2385,14 @@
 
    This :class:`bytearray` class method returns bytearray object, decoding
    the given string object.  The string must contain two hexadecimal digits
-   per byte, with ASCII spaces being ignored.
+   per byte, with ASCII whitespace being ignored.
 
    >>> bytearray.fromhex('2Ef0 F1f2  ')
    bytearray(b'.\xf0\xf1\xf2')
 
+   .. versionchanged:: 3.7
+      :meth:`bytearray.fromhex` now skips all ASCII whitespace in the string, not just spaces.
+
 A reverse conversion function exists to transform a bytearray object into its
 hexadecimal representation.
 
diff -r 3b4d00e20694 Doc/whatsnew/3.7.rst
--- a/Doc/whatsnew/3.7.rst	Mon Dec 19 22:05:46 2016 +0800
+++ b/Doc/whatsnew/3.7.rst	Mon Dec 19 09:56:38 2016 -0600
@@ -79,6 +79,8 @@
   now have more than 255 parameters.
   (Contributed by Serhiy Storchaka in :issue:`12844` and :issue:`18896`.)
 
+* :meth:`bytes.fromhex` and :meth:`bytearray.fromhex` now ignore all ASCII
+  whitespace, not only spaces. (Contributed by Robert Xiao in :issue:`28927`.)
 
 New Modules
 ===========
diff -r 3b4d00e20694 Lib/test/test_bytes.py
--- a/Lib/test/test_bytes.py	Mon Dec 19 22:05:46 2016 +0800
+++ b/Lib/test/test_bytes.py	Mon Dec 19 09:56:38 2016 -0600
@@ -293,6 +293,14 @@
         b = bytearray([0x1a, 0x2b, 0x30])
         self.assertEqual(self.type2test.fromhex('1a2B30'), b)
         self.assertEqual(self.type2test.fromhex('  1A 2B  30   '), b)
+
+        # check that ASCII whitespace is ignored
+        self.assertEqual(self.type2test.fromhex(' 1A\n2B\t30\v'), b)
+        for c in "\x09\x0A\x0B\x0C\x0D\x20":
+            self.assertEqual(self.type2test.fromhex(c), self.type2test())
+        for c in "\x1C\x1D\x1E\x1F\x85\xa0\u2000\u2002\u2028":
+            self.assertRaises(ValueError, self.type2test.fromhex, c)
+
         self.assertEqual(self.type2test.fromhex('0000'), b'\0\0')
         self.assertRaises(TypeError, self.type2test.fromhex, b'1B')
         self.assertRaises(ValueError, self.type2test.fromhex, 'a')
diff -r 3b4d00e20694 Objects/bytesobject.c
--- a/Objects/bytesobject.c	Mon Dec 19 22:05:46 2016 +0800
+++ b/Objects/bytesobject.c	Mon Dec 19 09:56:38 2016 -0600
@@ -2378,10 +2378,10 @@
     end = str + hexlen;
     while (str < end) {
         /* skip over spaces in the input */
-        if (*str == ' ') {
+        if (Py_ISSPACE(*str)) {
             do {
                 str++;
-            } while (*str == ' ');
+            } while (Py_ISSPACE(*str));
             if (str >= end)
                 break;
         }