diff --git a/requests/models.py b/requests/models.py
index b72ac64c..dcc51b09 100644
--- a/requests/models.py
+++ b/requests/models.py
@@ -324,7 +324,7 @@ class Request(object):
             if isinstance(path, str):
                 path = path.encode('utf-8')
 
-            path = requote_path(path)
+        path = requote_path(path)
 
         url = (urlunparse([ scheme, netloc, path, params, query, fragment ]))
 
@@ -352,9 +352,6 @@ class Request(object):
         if not path:
             path = '/'
 
-        if is_py3:
-            path = quote(path.encode('utf-8'))
-
         url.append(path)
 
         query = p.query
diff --git a/requests/utils.py b/requests/utils.py
index 0f23a527..abbc752a 100644
--- a/requests/utils.py
+++ b/requests/utils.py
@@ -396,6 +396,28 @@ def stream_decompress(iterator, mode='gzip'):
         if rv:
             yield rv
 
+# The unreserved URI characters (RFC 3986)
+UNRESERVED_SET = frozenset(
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
+    + "0123456789-._~")
+
+def unquote_unreserved(uri):
+    """Un-escape any percent-escape sequences in a URI that are unreserved
+    characters.
+    This leaves all reserved, illegal and non-ASCII bytes encoded.
+    """
+    parts = uri.split('%')
+    for i in range(1, len(parts)):
+        h = parts[i][0:2]
+        if len(h) == 2:
+            c = chr(int(h, 16))
+            if c in UNRESERVED_SET:
+                parts[i] = c + parts[i][2:]
+            else:
+                parts[i] = '%' + parts[i]
+        else:
+            parts[i] = '%' + parts[i]
+    return ''.join(parts)
 
 def requote_path(path):
     """Re-quote the given URL path component.
@@ -403,6 +425,8 @@ def requote_path(path):
     This function passes the given path through an unquote/quote cycle to
     ensure that it is fully and consistently quoted.
     """
-    parts = path.split(b"/")
-    parts = (quote(unquote(part), safe=b"") for part in parts)
-    return b"/".join(parts)
+    # Unquote only the unreserved characters
+    # Then quote only illegal characters (do not quote reserved, unreserved,
+    # or '%')
+    return quote(unquote_unreserved(path), safe="!#$%&'()*+,/:;=?@[]~")
+    return "/".join(parts)
diff --git a/test_requests.py b/test_requests.py
index eda9f791..2783a23b 100644
--- a/test_requests.py
+++ b/test_requests.py
@@ -74,9 +74,9 @@ class RequestsTestSuite(TestSetup, unittest.TestCase):
 
 
     def test_path_is_not_double_encoded(self):
-        request = requests.Request("http://0.0.0.0/get/~test")
+        request = requests.Request("http://0.0.0.0/get/test case")
 
-        assert request.path_url == "/get/%7Etest"
+        assert request.path_url == "/get/test%20case"
 
     def test_HTTP_200_OK_GET(self):
         r = get(httpbin('/get'))
@@ -117,6 +117,50 @@ class RequestsTestSuite(TestSetup, unittest.TestCase):
         requests.get(url=httpbin('get'), headers=heads)
 
 
+    def test_session_with_escaped_url(self):
+        # Test a URL that contains percent-escaped characters
+        # This URL should not be modified (double-escaped)
+        # Tests:
+        # - Quoted illegal characters ("%20" (' '), "%3C" ('<'), "%3E" ('>'))
+        # - Quoted reserved characters ("%25" ('%'), "%23" ('#'), "%2F" ('/'))
+        # - Quoted non-ASCII characters ("%C3%98", "%C3%A5")
+        path_fully_escaped = '%3Ca%25b%23c%2Fd%3E/%C3%98%20%C3%A5'
+        url = httpbin('get/' + path_fully_escaped)
+        response = get(url)
+        self.assertEqual(response.url, httpbin('get/' + path_fully_escaped))
+
+        # Test that illegal characters in a path get properly percent-escaped
+        # Tests:
+        # - Bare illegal characters (space, '<')
+        # - Bare non-ASCII characters ('\u00d8')
+        path = u'<a%25b%23c%2Fd%3E/\u00d8 %C3%A5'
+        url = httpbin('get/' + path)
+        response = get(url)
+        self.assertEqual(response.url, httpbin('get/' + path_fully_escaped))
+
+        # Test that reserved characters in a path do not get percent-escaped
+        # Tests:
+        # - All reserved characters (RFC 3986), except '?', '#', '[' and ']',
+        #   which are not allowed in the path, and ';' which delimits
+        #   parameters.
+        #   All such characters must be allowed bare in path, and must not be
+        #   encoded.
+        # - Special unreserved characters (RFC 3986), which should not be
+        #   encoded (even though it wouldn't hurt).
+        path_reserved = '!$&\'()*+,/:=@-._~'
+        url = httpbin('get/' + path_reserved)
+        response = get(url)
+        self.assertEqual(response.url, httpbin('get/' + path_reserved))
+
+        # Test that percent-encoded unreserved characters in a path get
+        # normalised to their un-encoded forms.
+        path_unreserved = 'ABCDwxyz1234-._~'
+        path_unreserved_escaped = '%41%42%43%44%77%78%79%7A%31%32%33%34%2D%2E%5F%7E'
+        url = httpbin('get/' + path_unreserved_escaped)
+        response = get(url)
+        self.assertEqual(response.url, httpbin('get/' + path_unreserved))
+
+
     def test_user_agent_transfers(self):
         """Issue XX"""