diff --git a/Doc/library/binascii.rst b/Doc/library/binascii.rst
index 89ecddc7780..98d8679fa3d 100644
--- a/Doc/library/binascii.rst
+++ b/Doc/library/binascii.rst
@@ -145,8 +145,8 @@ The :mod:`binascii` module defines the following functions:
       platforms, use ``crc32(data) & 0xffffffff``.
 
 
-.. function:: b2a_hex(data)
-              hexlify(data)
+.. function:: b2a_hex(data[, sep[, bytes_per_sep=1]])
+              hexlify(data[, sep[, bytes_per_sep=1]])
 
    Return the hexadecimal representation of the binary *data*.  Every byte of
    *data* is converted into the corresponding 2-digit hex representation.  The
@@ -155,6 +155,24 @@ The :mod:`binascii` module defines the following functions:
    Similar functionality (but returning a text string) is also conveniently
    accessible using the :meth:`bytes.hex` method.
 
+   If *sep* is specified, it must be a single character str or bytes object.
+   It will be inserted in the output after every *bytes_per_sep* input bytes.
+   Separator placement is counted from the right end of the output by default,
+   if you wish to count from the left, supply a negative *bytes_per_sep* value.
+
+      >>> import binascii
+      >>> binascii.b2a_hex(b'\xb9\x01\xef')
+      b'b901ef'
+      >>> binascii.hexlify(b'\xb9\x01\xef', '-')
+      b'b9-01-ef'
+      >>> binascii.b2a_hex(b'\xb9\x01\xef', b'_', 2)
+      b'b9_01ef'
+      >>> binascii.b2a_hex(b'\xb9\x01\xef', b' ', -2)
+      b'b901 ef'
+
+   .. versionchanged:: 3.8
+      The *sep* and *bytes_per_sep* parameters were added.
+
 .. function:: a2b_hex(hexstr)
               unhexlify(hexstr)
 
diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index 293a1ab6a0d..fcb0da74e15 100644
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -2404,8 +2404,26 @@ data and are closely related to string objects in a variety of other ways.
       >>> b'\xf0\xf1\xf2'.hex()
       'f0f1f2'
 
+      If you want to make the hex string easier to read, you can specify a
+      single character separator *sep* parameter to include in the output.
+      By default between each byte.  A second optional *bytes_per_sep*
+      parameter controls the spacing.  Positive values calculate the
+      separator position from the right, negative values from the left.
+
+      >>> value = b'\xf0\xf1\xf2'
+      >>> value.hex('-')
+      'f0-f1-f2'
+      >>> value.hex('_', 2)
+      'f0_f1f2'
+      >>> b'UUDDLRLRAB'.hex(' ', -4)
+      '55554444 4c524c52 4142'
+
       .. versionadded:: 3.5
 
+      .. versionchanged:: 3.8
+         :meth:`bytes.hex` now supports optional *sep* and *bytes_per_sep*
+         parameters to insert separators between bytes in the hex output.
+
 Since bytes objects are sequences of integers (akin to a tuple), for a bytes
 object *b*, ``b[0]`` will be an integer, while ``b[0:1]`` will be a bytes
 object of length 1.  (This contrasts with text strings, where both indexing
diff --git a/Include/pystrhex.h b/Include/pystrhex.h
index 66a30e2233c..a4f36305bac 100644
--- a/Include/pystrhex.h
+++ b/Include/pystrhex.h
@@ -10,6 +10,9 @@ extern "C" {
 PyAPI_FUNC(PyObject*) _Py_strhex(const char* argbuf, const Py_ssize_t arglen);
 /* Returns a bytes() containing the ASCII hex representation of argbuf. */
 PyAPI_FUNC(PyObject*) _Py_strhex_bytes(const char* argbuf, const Py_ssize_t arglen);
+/* These variants include support for a separator between every N bytes: */
+PyAPI_FUNC(PyObject*) _Py_strhex_with_sep(const char* argbuf, const Py_ssize_t arglen, const PyObject* sep, const int bytes_per_group);
+PyAPI_FUNC(PyObject*) _Py_strhex_bytes_with_sep(const char* argbuf, const Py_ssize_t arglen, const PyObject* sep, const int bytes_per_group);
 #endif /* !Py_LIMITED_API */
 
 #ifdef __cplusplus
diff --git a/Lib/test/test_binascii.py b/Lib/test/test_binascii.py
index 572e50c3e25..08de5c9fc7c 100644
--- a/Lib/test/test_binascii.py
+++ b/Lib/test/test_binascii.py
@@ -240,6 +240,18 @@ class BinASCIITest(unittest.TestCase):
         self.assertEqual(binascii.hexlify(self.type2test(s)), t)
         self.assertEqual(binascii.unhexlify(self.type2test(t)), u)
 
+    def test_hex_separator(self):
+        """Test that hexlify and b2a_hex are binary versions of bytes.hex."""
+        # Logic of separators is tested in test_bytes.py.  This checks that
+        # arg parsing works and exercises the direct to bytes object code
+        # path within pystrhex.c.
+        s = b'{s\005\000\000\000worldi\002\000\000\000s\005\000\000\000helloi\001\000\000\0000'
+        self.assertEqual(binascii.hexlify(self.type2test(s)), s.hex().encode('ascii'))
+        expected8 = s.hex('.', 8).encode('ascii')
+        self.assertEqual(binascii.hexlify(self.type2test(s), '.', 8), expected8)
+        expected1 = s.hex(':').encode('ascii')
+        self.assertEqual(binascii.b2a_hex(self.type2test(s), ':'), expected1)
+
     def test_qp(self):
         type2test = self.type2test
         a2b_qp = binascii.a2b_qp
diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py
index 9502a8f974b..bbd45c75298 100644
--- a/Lib/test/test_bytes.py
+++ b/Lib/test/test_bytes.py
@@ -417,6 +417,63 @@ class BaseBytesTest:
         self.assertEqual(self.type2test(b"\x1a\x2b\x30").hex(), '1a2b30')
         self.assertEqual(memoryview(b"\x1a\x2b\x30").hex(), '1a2b30')
 
+    def test_hex_separator_basics(self):
+        three_bytes = self.type2test(b'\xb9\x01\xef')
+        self.assertEqual(three_bytes.hex(), 'b901ef')
+        with self.assertRaises(ValueError):
+            three_bytes.hex('')
+        with self.assertRaises(ValueError):
+            three_bytes.hex('xx')
+        self.assertEqual(three_bytes.hex(':', 0), 'b901ef')
+        with self.assertRaises(TypeError):
+            three_bytes.hex(None, 0)
+        with self.assertRaises(ValueError):
+            three_bytes.hex('\xff')
+        with self.assertRaises(ValueError):
+            three_bytes.hex(b'\xff')
+        with self.assertRaises(ValueError):
+            three_bytes.hex(b'\x80')
+        with self.assertRaises(ValueError):
+            three_bytes.hex(chr(0x100))
+        self.assertEqual(three_bytes.hex(':', 0), 'b901ef')
+        self.assertEqual(three_bytes.hex(b'\x00'), 'b9\x0001\x00ef')
+        self.assertEqual(three_bytes.hex('\x00'), 'b9\x0001\x00ef')
+        self.assertEqual(three_bytes.hex(b'\x7f'), 'b9\x7f01\x7fef')
+        self.assertEqual(three_bytes.hex('\x7f'), 'b9\x7f01\x7fef')
+        self.assertEqual(three_bytes.hex(':', 3), 'b901ef')
+        self.assertEqual(three_bytes.hex(':', 4), 'b901ef')
+        self.assertEqual(three_bytes.hex(':', -4), 'b901ef')
+        self.assertEqual(three_bytes.hex(':'), 'b9:01:ef')
+        self.assertEqual(three_bytes.hex(b'$'), 'b9$01$ef')
+        self.assertEqual(three_bytes.hex(':', 1), 'b9:01:ef')
+        self.assertEqual(three_bytes.hex(':', -1), 'b9:01:ef')
+        self.assertEqual(three_bytes.hex(':', 2), 'b9:01ef')
+        self.assertEqual(three_bytes.hex(':', 1), 'b9:01:ef')
+        self.assertEqual(three_bytes.hex('*', -2), 'b901*ef')
+
+        value = b'{s\005\000\000\000worldi\002\000\000\000s\005\000\000\000helloi\001\000\000\0000'
+        self.assertEqual(value.hex('.', 8), '7b7305000000776f.726c646902000000.730500000068656c.6c6f690100000030')
+
+    def test_hex_separator_five_bytes(self):
+        five_bytes = self.type2test(range(90,95))
+        self.assertEqual(five_bytes.hex(), '5a5b5c5d5e')
+
+    def test_hex_separator_six_bytes(self):
+        six_bytes = self.type2test(x*3 for x in range(1, 7))
+        self.assertEqual(six_bytes.hex(), '0306090c0f12')
+        self.assertEqual(six_bytes.hex('.', 1), '03.06.09.0c.0f.12')
+        self.assertEqual(six_bytes.hex(' ', 2), '0306 090c 0f12')
+        self.assertEqual(six_bytes.hex('-', 3), '030609-0c0f12')
+        self.assertEqual(six_bytes.hex(':', 4), '0306:090c0f12')
+        self.assertEqual(six_bytes.hex(':', 5), '03:06090c0f12')
+        self.assertEqual(six_bytes.hex(':', 6), '0306090c0f12')
+        self.assertEqual(six_bytes.hex(':', 95), '0306090c0f12')
+        self.assertEqual(six_bytes.hex('_', -3), '030609_0c0f12')
+        self.assertEqual(six_bytes.hex(':', -4), '0306090c:0f12')
+        self.assertEqual(six_bytes.hex(b'@', -5), '0306090c0f@12')
+        self.assertEqual(six_bytes.hex(':', -6), '0306090c0f12')
+        self.assertEqual(six_bytes.hex(' ', -95), '0306090c0f12')
+
     def test_join(self):
         self.assertEqual(self.type2test(b"").join([]), b"")
         self.assertEqual(self.type2test(b"").join([b""]), b"")
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index f1013f25725..5ea18f52c4f 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -665,11 +665,13 @@ plain ol' Python and is guaranteed to be available.
     True
     >>> real_tests = [t for t in tests if len(t.examples) > 0]
     >>> len(real_tests) # objects that actually have doctests
-    9
+    12
     >>> for t in real_tests:
     ...     print('{}  {}'.format(len(t.examples), t.name))
     ...
     1  builtins.bin
+    5  builtins.bytearray.hex
+    5  builtins.bytes.hex
     3  builtins.float.as_integer_ratio
     2  builtins.float.fromhex
     2  builtins.float.hex
@@ -677,6 +679,7 @@ plain ol' Python and is guaranteed to be available.
     1  builtins.int
     3  builtins.int.as_integer_ratio
     2  builtins.int.bit_length
+    5  builtins.memoryview.hex
     1  builtins.oct
 
 Note here that 'bin', 'oct', and 'hex' are functions; 'float.as_integer_ratio',
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-05-25-17-18-26.bpo-22385.VeVvhJ.rst b/Misc/NEWS.d/next/Core and Builtins/2019-05-25-17-18-26.bpo-22385.VeVvhJ.rst
new file mode 100644
index 00000000000..e10690b3a56
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-05-25-17-18-26.bpo-22385.VeVvhJ.rst	
@@ -0,0 +1,4 @@
+The `bytes.hex`, `bytearray.hex`, and `memoryview.hex` methods as well as
+the `binascii.hexlify` and `b2a_hex` functions now have the ability to
+include an optional separator between hex bytes.  This functionality was
+inspired by MicroPython's hexlify implementation.
diff --git a/Modules/binascii.c b/Modules/binascii.c
index d22ab7b4683..1c7dc35882d 100644
--- a/Modules/binascii.c
+++ b/Modules/binascii.c
@@ -1159,19 +1159,33 @@ binascii_crc32_impl(PyObject *module, Py_buffer *data, unsigned int crc)
 binascii.b2a_hex
 
     data: Py_buffer
-    /
+    sep: object = NULL
+        An optional single character or byte to separate hex bytes.
+    bytes_per_sep: int = 1
+        How many bytes between separators.  Positive values count from the
+        right, negative values count from the left.
 
 Hexadecimal representation of binary data.
 
 The return value is a bytes object.  This function is also
 available as "hexlify()".
+
+Example:
+>>> binascii.b2a_hex(b'\xb9\x01\xef')
+b'b901ef'
+>>> binascii.hexlify(b'\xb9\x01\xef', ':')
+b'b9:01:ef'
+>>> binascii.b2a_hex(b'\xb9\x01\xef', b'_', 2)
+b'b9_01ef'
 [clinic start generated code]*/
 
 static PyObject *
-binascii_b2a_hex_impl(PyObject *module, Py_buffer *data)
-/*[clinic end generated code: output=92fec1a95c9897a0 input=96423cfa299ff3b1]*/
+binascii_b2a_hex_impl(PyObject *module, Py_buffer *data, PyObject *sep,
+                      int bytes_per_sep)
+/*[clinic end generated code: output=a26937946a81d2c7 input=ec0ade6ba2e43543]*/
 {
-    return _Py_strhex_bytes((const char *)data->buf, data->len);
+    return _Py_strhex_bytes_with_sep((const char *)data->buf, data->len,
+                                     sep, bytes_per_sep);
 }
 
 /*[clinic input]
@@ -1179,14 +1193,17 @@ binascii.hexlify = binascii.b2a_hex
 
 Hexadecimal representation of binary data.
 
-The return value is a bytes object.
+The return value is a bytes object.  This function is also
+available as "b2a_hex()".
 [clinic start generated code]*/
 
 static PyObject *
-binascii_hexlify_impl(PyObject *module, Py_buffer *data)
-/*[clinic end generated code: output=749e95e53c14880c input=2e3afae7f083f061]*/
+binascii_hexlify_impl(PyObject *module, Py_buffer *data, PyObject *sep,
+                      int bytes_per_sep)
+/*[clinic end generated code: output=d12aa1b001b15199 input=bc317bd4e241f76b]*/
 {
-    return _Py_strhex_bytes((const char *)data->buf, data->len);
+    return _Py_strhex_bytes_with_sep((const char *)data->buf, data->len,
+                                     sep, bytes_per_sep);
 }
 
 /*[clinic input]
diff --git a/Modules/clinic/binascii.c.h b/Modules/clinic/binascii.c.h
index 4043d89d97d..d4850485690 100644
--- a/Modules/clinic/binascii.c.h
+++ b/Modules/clinic/binascii.c.h
@@ -432,34 +432,78 @@ exit:
 }
 
 PyDoc_STRVAR(binascii_b2a_hex__doc__,
-"b2a_hex($module, data, /)\n"
+"b2a_hex($module, /, data, sep=None, bytes_per_sep=1)\n"
 "--\n"
 "\n"
 "Hexadecimal representation of binary data.\n"
 "\n"
+"  sep\n"
+"    An optional single character or byte to separate hex bytes.\n"
+"  bytes_per_sep\n"
+"    How many bytes between separators.  Positive values count from the\n"
+"    right, negative values count from the left.\n"
+"\n"
 "The return value is a bytes object.  This function is also\n"
-"available as \"hexlify()\".");
+"available as \"hexlify()\".\n"
+"\n"
+"Example:\n"
+">>> binascii.b2a_hex(b\'\\xb9\\x01\\xef\')\n"
+"b\'b901ef\'\n"
+">>> binascii.hexlify(b\'\\xb9\\x01\\xef\', \':\')\n"
+"b\'b9:01:ef\'\n"
+">>> binascii.b2a_hex(b\'\\xb9\\x01\\xef\', b\'_\', 2)\n"
+"b\'b9_01ef\'");
 
 #define BINASCII_B2A_HEX_METHODDEF    \
-    {"b2a_hex", (PyCFunction)binascii_b2a_hex, METH_O, binascii_b2a_hex__doc__},
+    {"b2a_hex", (PyCFunction)(void(*)(void))binascii_b2a_hex, METH_FASTCALL|METH_KEYWORDS, binascii_b2a_hex__doc__},
 
 static PyObject *
-binascii_b2a_hex_impl(PyObject *module, Py_buffer *data);
+binascii_b2a_hex_impl(PyObject *module, Py_buffer *data, PyObject *sep,
+                      int bytes_per_sep);
 
 static PyObject *
-binascii_b2a_hex(PyObject *module, PyObject *arg)
+binascii_b2a_hex(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"data", "sep", "bytes_per_sep", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "b2a_hex", 0};
+    PyObject *argsbuf[3];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 1;
     Py_buffer data = {NULL, NULL};
+    PyObject *sep = NULL;
+    int bytes_per_sep = 1;
 
-    if (PyObject_GetBuffer(arg, &data, PyBUF_SIMPLE) != 0) {
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 1, 3, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (PyObject_GetBuffer(args[0], &data, PyBUF_SIMPLE) != 0) {
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&data, 'C')) {
-        _PyArg_BadArgument("b2a_hex", 0, "contiguous buffer", arg);
+        _PyArg_BadArgument("b2a_hex", 1, "contiguous buffer", args[0]);
         goto exit;
     }
-    return_value = binascii_b2a_hex_impl(module, &data);
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[1]) {
+        sep = args[1];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (PyFloat_Check(args[2])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    bytes_per_sep = _PyLong_AsInt(args[2]);
+    if (bytes_per_sep == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional_pos:
+    return_value = binascii_b2a_hex_impl(module, &data, sep, bytes_per_sep);
 
 exit:
     /* Cleanup for data */
@@ -471,33 +515,70 @@ exit:
 }
 
 PyDoc_STRVAR(binascii_hexlify__doc__,
-"hexlify($module, data, /)\n"
+"hexlify($module, /, data, sep=None, bytes_per_sep=1)\n"
 "--\n"
 "\n"
 "Hexadecimal representation of binary data.\n"
 "\n"
-"The return value is a bytes object.");
+"  sep\n"
+"    An optional single character or byte to separate hex bytes.\n"
+"  bytes_per_sep\n"
+"    How many bytes between separators.  Positive values count from the\n"
+"    right, negative values count from the left.\n"
+"\n"
+"The return value is a bytes object.  This function is also\n"
+"available as \"b2a_hex()\".");
 
 #define BINASCII_HEXLIFY_METHODDEF    \
-    {"hexlify", (PyCFunction)binascii_hexlify, METH_O, binascii_hexlify__doc__},
+    {"hexlify", (PyCFunction)(void(*)(void))binascii_hexlify, METH_FASTCALL|METH_KEYWORDS, binascii_hexlify__doc__},
 
 static PyObject *
-binascii_hexlify_impl(PyObject *module, Py_buffer *data);
+binascii_hexlify_impl(PyObject *module, Py_buffer *data, PyObject *sep,
+                      int bytes_per_sep);
 
 static PyObject *
-binascii_hexlify(PyObject *module, PyObject *arg)
+binascii_hexlify(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"data", "sep", "bytes_per_sep", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "hexlify", 0};
+    PyObject *argsbuf[3];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 1;
     Py_buffer data = {NULL, NULL};
+    PyObject *sep = NULL;
+    int bytes_per_sep = 1;
 
-    if (PyObject_GetBuffer(arg, &data, PyBUF_SIMPLE) != 0) {
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 1, 3, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (PyObject_GetBuffer(args[0], &data, PyBUF_SIMPLE) != 0) {
         goto exit;
     }
     if (!PyBuffer_IsContiguous(&data, 'C')) {
-        _PyArg_BadArgument("hexlify", 0, "contiguous buffer", arg);
+        _PyArg_BadArgument("hexlify", 1, "contiguous buffer", args[0]);
         goto exit;
     }
-    return_value = binascii_hexlify_impl(module, &data);
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[1]) {
+        sep = args[1];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (PyFloat_Check(args[2])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    bytes_per_sep = _PyLong_AsInt(args[2]);
+    if (bytes_per_sep == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional_pos:
+    return_value = binascii_hexlify_impl(module, &data, sep, bytes_per_sep);
 
 exit:
     /* Cleanup for data */
@@ -720,4 +801,4 @@ exit:
 
     return return_value;
 }
-/*[clinic end generated code: output=a4a38e162605aca2 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=f7b8049edb130c63 input=a9049054013a1b77]*/
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index c7c28312b00..b9fcc01b703 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -2020,18 +2020,36 @@ bytearray_fromhex_impl(PyTypeObject *type, PyObject *string)
     return result;
 }
 
-PyDoc_STRVAR(hex__doc__,
-"B.hex() -> string\n\
-\n\
-Create a string of hexadecimal numbers from a bytearray object.\n\
-Example: bytearray([0xb9, 0x01, 0xef]).hex() -> 'b901ef'.");
+/*[clinic input]
+bytearray.hex
+
+    sep: object = NULL
+        An optional single character or byte to separate hex bytes.
+    bytes_per_sep: int = 1
+        How many bytes between separators.  Positive values count from the
+        right, negative values count from the left.
+
+Create a str of hexadecimal numbers from a bytearray object.
+
+Example:
+>>> value = bytearray([0xb9, 0x01, 0xef])
+>>> value.hex()
+'b901ef'
+>>> value.hex(':')
+'b9:01:ef'
+>>> value.hex(':', 2)
+'b9:01ef'
+>>> value.hex(':', -2)
+'b901:ef'
+[clinic start generated code]*/
 
 static PyObject *
-bytearray_hex(PyBytesObject *self, PyObject *Py_UNUSED(ignored))
+bytearray_hex_impl(PyByteArrayObject *self, PyObject *sep, int bytes_per_sep)
+/*[clinic end generated code: output=29c4e5ef72c565a0 input=814c15830ac8c4b5]*/
 {
     char* argbuf = PyByteArray_AS_STRING(self);
     Py_ssize_t arglen = PyByteArray_GET_SIZE(self);
-    return _Py_strhex(argbuf, arglen);
+    return _Py_strhex_with_sep(argbuf, arglen, sep, bytes_per_sep);
 }
 
 static PyObject *
@@ -2160,7 +2178,7 @@ bytearray_methods[] = {
     {"find", (PyCFunction)bytearray_find, METH_VARARGS,
      _Py_find__doc__},
     BYTEARRAY_FROMHEX_METHODDEF
-    {"hex", (PyCFunction)bytearray_hex, METH_NOARGS, hex__doc__},
+    BYTEARRAY_HEX_METHODDEF
     {"index", (PyCFunction)bytearray_index, METH_VARARGS, _Py_index__doc__},
     BYTEARRAY_INSERT_METHODDEF
     {"isalnum", stringlib_isalnum, METH_NOARGS,
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 6f34037154d..bf7c7da423b 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -2416,18 +2416,36 @@ _PyBytes_FromHex(PyObject *string, int use_bytearray)
     return NULL;
 }
 
-PyDoc_STRVAR(hex__doc__,
-"B.hex() -> string\n\
-\n\
-Create a string of hexadecimal numbers from a bytes object.\n\
-Example: b'\\xb9\\x01\\xef'.hex() -> 'b901ef'.");
+/*[clinic input]
+bytes.hex
+
+    sep: object = NULL
+        An optional single character or byte to separate hex bytes.
+    bytes_per_sep: int = 1
+        How many bytes between separators.  Positive values count from the
+        right, negative values count from the left.
+
+Create a str of hexadecimal numbers from a bytes object.
+
+Example:
+>>> value = b'\xb9\x01\xef'
+>>> value.hex()
+'b901ef'
+>>> value.hex(':')
+'b9:01:ef'
+>>> value.hex(':', 2)
+'b9:01ef'
+>>> value.hex(':', -2)
+'b901:ef'
+[clinic start generated code]*/
 
 static PyObject *
-bytes_hex(PyBytesObject *self, PyObject *Py_UNUSED(ignored))
+bytes_hex_impl(PyBytesObject *self, PyObject *sep, int bytes_per_sep)
+/*[clinic end generated code: output=1f134da504064139 input=f1238d3455990218]*/
 {
     char* argbuf = PyBytes_AS_STRING(self);
     Py_ssize_t arglen = PyBytes_GET_SIZE(self);
-    return _Py_strhex(argbuf, arglen);
+    return _Py_strhex_with_sep(argbuf, arglen, sep, bytes_per_sep);
 }
 
 static PyObject *
@@ -2452,7 +2470,7 @@ bytes_methods[] = {
     {"find", (PyCFunction)bytes_find, METH_VARARGS,
      _Py_find__doc__},
     BYTES_FROMHEX_METHODDEF
-    {"hex", (PyCFunction)bytes_hex, METH_NOARGS, hex__doc__},
+    BYTES_HEX_METHODDEF
     {"index", (PyCFunction)bytes_index, METH_VARARGS, _Py_index__doc__},
     {"isalnum", stringlib_isalnum, METH_NOARGS,
      _Py_isalnum__doc__},
diff --git a/Objects/clinic/bytearrayobject.c.h b/Objects/clinic/bytearrayobject.c.h
index da1dc6a40af..08c6eb53f58 100644
--- a/Objects/clinic/bytearrayobject.c.h
+++ b/Objects/clinic/bytearrayobject.c.h
@@ -867,6 +867,75 @@ exit:
     return return_value;
 }
 
+PyDoc_STRVAR(bytearray_hex__doc__,
+"hex($self, /, sep=None, bytes_per_sep=1)\n"
+"--\n"
+"\n"
+"Create a str of hexadecimal numbers from a bytearray object.\n"
+"\n"
+"  sep\n"
+"    An optional single character or byte to separate hex bytes.\n"
+"  bytes_per_sep\n"
+"    How many bytes between separators.  Positive values count from the\n"
+"    right, negative values count from the left.\n"
+"\n"
+"Example:\n"
+">>> value = bytearray([0xb9, 0x01, 0xef])\n"
+">>> value.hex()\n"
+"\'b901ef\'\n"
+">>> value.hex(\':\')\n"
+"\'b9:01:ef\'\n"
+">>> value.hex(\':\', 2)\n"
+"\'b9:01ef\'\n"
+">>> value.hex(\':\', -2)\n"
+"\'b901:ef\'");
+
+#define BYTEARRAY_HEX_METHODDEF    \
+    {"hex", (PyCFunction)(void(*)(void))bytearray_hex, METH_FASTCALL|METH_KEYWORDS, bytearray_hex__doc__},
+
+static PyObject *
+bytearray_hex_impl(PyByteArrayObject *self, PyObject *sep, int bytes_per_sep);
+
+static PyObject *
+bytearray_hex(PyByteArrayObject *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"sep", "bytes_per_sep", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "hex", 0};
+    PyObject *argsbuf[2];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
+    PyObject *sep = NULL;
+    int bytes_per_sep = 1;
+
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 2, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[0]) {
+        sep = args[0];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    bytes_per_sep = _PyLong_AsInt(args[1]);
+    if (bytes_per_sep == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional_pos:
+    return_value = bytearray_hex_impl(self, sep, bytes_per_sep);
+
+exit:
+    return return_value;
+}
+
 PyDoc_STRVAR(bytearray_reduce__doc__,
 "__reduce__($self, /)\n"
 "--\n"
@@ -942,4 +1011,4 @@ bytearray_sizeof(PyByteArrayObject *self, PyObject *Py_UNUSED(ignored))
 {
     return bytearray_sizeof_impl(self);
 }
-/*[clinic end generated code: output=272fcb836b92da32 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=7848247e5469ba1b input=a9049054013a1b77]*/
diff --git a/Objects/clinic/bytesobject.c.h b/Objects/clinic/bytesobject.c.h
index b03078305a6..69c35063c6c 100644
--- a/Objects/clinic/bytesobject.c.h
+++ b/Objects/clinic/bytesobject.c.h
@@ -686,4 +686,73 @@ bytes_fromhex(PyTypeObject *type, PyObject *arg)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=af9f51b9b185567d input=a9049054013a1b77]*/
+
+PyDoc_STRVAR(bytes_hex__doc__,
+"hex($self, /, sep=None, bytes_per_sep=1)\n"
+"--\n"
+"\n"
+"Create a str of hexadecimal numbers from a bytes object.\n"
+"\n"
+"  sep\n"
+"    An optional single character or byte to separate hex bytes.\n"
+"  bytes_per_sep\n"
+"    How many bytes between separators.  Positive values count from the\n"
+"    right, negative values count from the left.\n"
+"\n"
+"Example:\n"
+">>> value = b\'\\xb9\\x01\\xef\'\n"
+">>> value.hex()\n"
+"\'b901ef\'\n"
+">>> value.hex(\':\')\n"
+"\'b9:01:ef\'\n"
+">>> value.hex(\':\', 2)\n"
+"\'b9:01ef\'\n"
+">>> value.hex(\':\', -2)\n"
+"\'b901:ef\'");
+
+#define BYTES_HEX_METHODDEF    \
+    {"hex", (PyCFunction)(void(*)(void))bytes_hex, METH_FASTCALL|METH_KEYWORDS, bytes_hex__doc__},
+
+static PyObject *
+bytes_hex_impl(PyBytesObject *self, PyObject *sep, int bytes_per_sep);
+
+static PyObject *
+bytes_hex(PyBytesObject *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"sep", "bytes_per_sep", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "hex", 0};
+    PyObject *argsbuf[2];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
+    PyObject *sep = NULL;
+    int bytes_per_sep = 1;
+
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 2, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[0]) {
+        sep = args[0];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    bytes_per_sep = _PyLong_AsInt(args[1]);
+    if (bytes_per_sep == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional_pos:
+    return_value = bytes_hex_impl(self, sep, bytes_per_sep);
+
+exit:
+    return return_value;
+}
+/*[clinic end generated code: output=2d0a3733e13e753a input=a9049054013a1b77]*/
diff --git a/Objects/clinic/memoryobject.c.h b/Objects/clinic/memoryobject.c.h
new file mode 100644
index 00000000000..64fce10acb5
--- /dev/null
+++ b/Objects/clinic/memoryobject.c.h
@@ -0,0 +1,74 @@
+/*[clinic input]
+preserve
+[clinic start generated code]*/
+
+PyDoc_STRVAR(memoryview_hex__doc__,
+"hex($self, /, sep=None, bytes_per_sep=1)\n"
+"--\n"
+"\n"
+"Return the data in the buffer as a str of hexadecimal numbers.\n"
+"\n"
+"  sep\n"
+"    An optional single character or byte to separate hex bytes.\n"
+"  bytes_per_sep\n"
+"    How many bytes between separators.  Positive values count from the\n"
+"    right, negative values count from the left.\n"
+"\n"
+"Example:\n"
+">>> value = memoryview(b\'\\xb9\\x01\\xef\')\n"
+">>> value.hex()\n"
+"\'b901ef\'\n"
+">>> value.hex(\':\')\n"
+"\'b9:01:ef\'\n"
+">>> value.hex(\':\', 2)\n"
+"\'b9:01ef\'\n"
+">>> value.hex(\':\', -2)\n"
+"\'b901:ef\'");
+
+#define MEMORYVIEW_HEX_METHODDEF    \
+    {"hex", (PyCFunction)(void(*)(void))memoryview_hex, METH_FASTCALL|METH_KEYWORDS, memoryview_hex__doc__},
+
+static PyObject *
+memoryview_hex_impl(PyMemoryViewObject *self, PyObject *sep,
+                    int bytes_per_sep);
+
+static PyObject *
+memoryview_hex(PyMemoryViewObject *self, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
+{
+    PyObject *return_value = NULL;
+    static const char * const _keywords[] = {"sep", "bytes_per_sep", NULL};
+    static _PyArg_Parser _parser = {NULL, _keywords, "hex", 0};
+    PyObject *argsbuf[2];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
+    PyObject *sep = NULL;
+    int bytes_per_sep = 1;
+
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 2, 0, argsbuf);
+    if (!args) {
+        goto exit;
+    }
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[0]) {
+        sep = args[0];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+    if (PyFloat_Check(args[1])) {
+        PyErr_SetString(PyExc_TypeError,
+                        "integer argument expected, got float" );
+        goto exit;
+    }
+    bytes_per_sep = _PyLong_AsInt(args[1]);
+    if (bytes_per_sep == -1 && PyErr_Occurred()) {
+        goto exit;
+    }
+skip_optional_pos:
+    return_value = memoryview_hex_impl(self, sep, bytes_per_sep);
+
+exit:
+    return return_value;
+}
+/*[clinic end generated code: output=5e44e2bcf01057b5 input=a9049054013a1b77]*/
diff --git a/Objects/memoryobject.c b/Objects/memoryobject.c
index 6bbb413c3c1..3955c58ee5d 100644
--- a/Objects/memoryobject.c
+++ b/Objects/memoryobject.c
@@ -7,6 +7,12 @@
 #include "pystrhex.h"
 #include <stddef.h>
 
+/*[clinic input]
+class memoryview "PyMemoryViewObject *" "&PyMemoryView_Type"
+[clinic start generated code]*/
+/*[clinic end generated code: output=da39a3ee5e6b4b0d input=e2e49d2192835219]*/
+
+#include "clinic/memoryobject.c.h"
 
 /****************************************************************************/
 /*                           ManagedBuffer Object                           */
@@ -2160,8 +2166,33 @@ memory_tobytes(PyMemoryViewObject *self, PyObject *args, PyObject *kwds)
     return bytes;
 }
 
+/*[clinic input]
+memoryview.hex
+
+    sep: object = NULL
+        An optional single character or byte to separate hex bytes.
+    bytes_per_sep: int = 1
+        How many bytes between separators.  Positive values count from the
+        right, negative values count from the left.
+
+Return the data in the buffer as a str of hexadecimal numbers.
+
+Example:
+>>> value = memoryview(b'\xb9\x01\xef')
+>>> value.hex()
+'b901ef'
+>>> value.hex(':')
+'b9:01:ef'
+>>> value.hex(':', 2)
+'b9:01ef'
+>>> value.hex(':', -2)
+'b901:ef'
+[clinic start generated code]*/
+
 static PyObject *
-memory_hex(PyMemoryViewObject *self, PyObject *dummy)
+memoryview_hex_impl(PyMemoryViewObject *self, PyObject *sep,
+                    int bytes_per_sep)
+/*[clinic end generated code: output=430ca760f94f3ca7 input=539f6a3a5fb56946]*/
 {
     Py_buffer *src = VIEW_ADDR(self);
     PyObject *bytes;
@@ -2170,7 +2201,7 @@ memory_hex(PyMemoryViewObject *self, PyObject *dummy)
     CHECK_RELEASED(self);
 
     if (MV_C_CONTIGUOUS(self->flags)) {
-        return _Py_strhex(src->buf, src->len);
+        return _Py_strhex_with_sep(src->buf, src->len, sep, bytes_per_sep);
     }
 
     bytes = PyBytes_FromStringAndSize(NULL, src->len);
@@ -2182,7 +2213,9 @@ memory_hex(PyMemoryViewObject *self, PyObject *dummy)
         return NULL;
     }
 
-    ret = _Py_strhex(PyBytes_AS_STRING(bytes), PyBytes_GET_SIZE(bytes));
+    ret = _Py_strhex_with_sep(
+            PyBytes_AS_STRING(bytes), PyBytes_GET_SIZE(bytes),
+            sep, bytes_per_sep);
     Py_DECREF(bytes);
 
     return ret;
@@ -3090,10 +3123,6 @@ When order is 'C' or 'F', the data of the original array is converted to C or\n\
 Fortran order. For contiguous views, 'A' returns an exact copy of the physical\n\
 memory. In particular, in-memory Fortran order is preserved. For non-contiguous\n\
 views, the data is converted to C first. order=None is the same as order='C'.");
-PyDoc_STRVAR(memory_hex_doc,
-"hex($self, /)\n--\n\
-\n\
-Return the data in the buffer as a string of hexadecimal numbers.");
 PyDoc_STRVAR(memory_tolist_doc,
 "tolist($self, /)\n--\n\
 \n\
@@ -3110,7 +3139,7 @@ Return a readonly version of the memoryview.");
 static PyMethodDef memory_methods[] = {
     {"release",     (PyCFunction)memory_release, METH_NOARGS, memory_release_doc},
     {"tobytes",     (PyCFunction)(void(*)(void))memory_tobytes, METH_VARARGS|METH_KEYWORDS, memory_tobytes_doc},
-    {"hex",         (PyCFunction)memory_hex, METH_NOARGS, memory_hex_doc},
+    MEMORYVIEW_HEX_METHODDEF
     {"tolist",      (PyCFunction)memory_tolist, METH_NOARGS, memory_tolist_doc},
     {"cast",        (PyCFunction)(void(*)(void))memory_cast, METH_VARARGS|METH_KEYWORDS, memory_cast_doc},
     {"toreadonly",  (PyCFunction)memory_toreadonly, METH_NOARGS, memory_toreadonly_doc},
diff --git a/Python/pystrhex.c b/Python/pystrhex.c
index 028f187c707..695a3c394e9 100644
--- a/Python/pystrhex.c
+++ b/Python/pystrhex.c
@@ -5,40 +5,96 @@
 #include "pystrhex.h"
 
 static PyObject *_Py_strhex_impl(const char* argbuf, const Py_ssize_t arglen,
-                                 int return_bytes)
+                                 const PyObject* sep, int bytes_per_sep_group,
+                                 const int return_bytes)
 {
     PyObject *retval;
     Py_UCS1* retbuf;
-    Py_ssize_t i, j;
+    Py_ssize_t i, j, resultlen = 0;
+    Py_UCS1 sep_char;
+    unsigned int abs_bytes_per_sep;
+
+    if (sep) {
+        Py_ssize_t seplen = PyObject_Length(sep);
+        if (seplen < 0) {
+            return NULL;
+        }
+        if (seplen != 1) {
+            PyErr_SetString(PyExc_ValueError, "sep must be length 1.");
+            return NULL;
+        }
+        if (PyUnicode_Check(sep)) {
+            if (PyUnicode_READY(sep))
+                return NULL;
+            if (PyUnicode_KIND(sep) != PyUnicode_1BYTE_KIND) {
+                PyErr_SetString(PyExc_ValueError, "sep must be ASCII.");
+                return NULL;
+            }
+            sep_char = PyUnicode_READ_CHAR(sep, 0);
+        } else if (PyBytes_Check(sep)) {
+            sep_char = PyBytes_AS_STRING(sep)[0];
+        } else {
+            PyErr_SetString(PyExc_TypeError, "sep must be str or bytes.");
+            return NULL;
+        }
+        if (sep_char > 127 && !return_bytes) {
+            PyErr_SetString(PyExc_ValueError, "sep must be ASCII.");
+            return NULL;
+        }
+    } else {
+        bytes_per_sep_group = 0;
+    }
 
     assert(arglen >= 0);
-    if (arglen > PY_SSIZE_T_MAX / 2)
+    abs_bytes_per_sep = abs(bytes_per_sep_group);
+    if (bytes_per_sep_group && arglen > 0) {
+        /* How many sep characters we'll be inserting. */
+        resultlen = (arglen - 1) / abs_bytes_per_sep;
+    }
+    /* Bounds checking for our Py_ssize_t indices. */
+    if (arglen >= PY_SSIZE_T_MAX / 2 - resultlen) {
         return PyErr_NoMemory();
+    }
+    resultlen += arglen * 2;
+
+    if (abs_bytes_per_sep >= arglen) {
+        bytes_per_sep_group = 0;
+        abs_bytes_per_sep = 0;
+    }
 
     if (return_bytes) {
         /* If _PyBytes_FromSize() were public we could avoid malloc+copy. */
-        retbuf = (Py_UCS1*) PyMem_Malloc(arglen*2);
+        retbuf = (Py_UCS1*) PyMem_Malloc(resultlen);
         if (!retbuf)
             return PyErr_NoMemory();
         retval = NULL;  /* silence a compiler warning, assigned later. */
     } else {
-        retval = PyUnicode_New(arglen*2, 127);
+        retval = PyUnicode_New(resultlen, 127);
         if (!retval)
             return NULL;
         retbuf = PyUnicode_1BYTE_DATA(retval);
     }
 
-    /* make hex version of string, taken from shamodule.c */
-    for (i=j=0; i < arglen; i++) {
+    /* Hexlify */
+    for (i=j=0; i < arglen; ++i) {
+        assert(j < resultlen);
         unsigned char c;
         c = (argbuf[i] >> 4) & 0xf;
         retbuf[j++] = Py_hexdigits[c];
         c = argbuf[i] & 0xf;
         retbuf[j++] = Py_hexdigits[c];
+        if (bytes_per_sep_group && i < arglen - 1) {
+            Py_ssize_t anchor;
+            anchor = (bytes_per_sep_group > 0) ? (arglen - 1 - i) : (i + 1);
+            if (anchor % abs_bytes_per_sep == 0) {
+                retbuf[j++] = sep_char;
+            }
+        }
     }
+    assert(j == resultlen);
 
     if (return_bytes) {
-        retval = PyBytes_FromStringAndSize((const char *)retbuf, arglen*2);
+        retval = PyBytes_FromStringAndSize((const char *)retbuf, resultlen);
         PyMem_Free(retbuf);
     }
 #ifdef Py_DEBUG
@@ -52,12 +108,26 @@ static PyObject *_Py_strhex_impl(const char* argbuf, const Py_ssize_t arglen,
 
 PyObject * _Py_strhex(const char* argbuf, const Py_ssize_t arglen)
 {
-    return _Py_strhex_impl(argbuf, arglen, 0);
+    return _Py_strhex_impl(argbuf, arglen, NULL, 0, 0);
 }
 
 /* Same as above but returns a bytes() instead of str() to avoid the
  * need to decode the str() when bytes are needed. */
 PyObject * _Py_strhex_bytes(const char* argbuf, const Py_ssize_t arglen)
 {
-    return _Py_strhex_impl(argbuf, arglen, 1);
+    return _Py_strhex_impl(argbuf, arglen, NULL, 0, 1);
+}
+
+/* These variants include support for a separator between every N bytes: */
+
+PyObject * _Py_strhex_with_sep(const char* argbuf, const Py_ssize_t arglen, const PyObject* sep, const int bytes_per_group)
+{
+    return _Py_strhex_impl(argbuf, arglen, sep, bytes_per_group, 0);
+}
+
+/* Same as above but returns a bytes() instead of str() to avoid the
+ * need to decode the str() when bytes are needed. */
+PyObject * _Py_strhex_bytes_with_sep(const char* argbuf, const Py_ssize_t arglen, const PyObject* sep, const int bytes_per_group)
+{
+    return _Py_strhex_impl(argbuf, arglen, sep, bytes_per_group, 1);
 }