diff --git a/Lib/lib2to3/Grammar.txt b/Lib/lib2to3/Grammar.txt
index 51f5820..e007dc1 100644
--- a/Lib/lib2to3/Grammar.txt
+++ b/Lib/lib2to3/Grammar.txt
@@ -67,8 +67,8 @@
 
 compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated | async_stmt
 async_stmt: ASYNC (funcdef | with_stmt | for_stmt)
-if_stmt: 'if' test ':' suite ('elif' test ':' suite)* ['else' ':' suite]
-while_stmt: 'while' test ':' suite ['else' ':' suite]
+if_stmt: 'if' namedexpr_test ':' suite ('elif' namedexpr_test ':' suite)* ['else' ':' suite]
+while_stmt: 'while' namedexpr_test ':' suite ['else' ':' suite]
 for_stmt: 'for' exprlist 'in' testlist ':' suite ['else' ':' suite]
 try_stmt: ('try' ':' suite
            ((except_clause ':' suite)+
@@ -91,6 +91,7 @@
 old_test: or_test | old_lambdef
 old_lambdef: 'lambda' [varargslist] ':' old_test
 
+namedexpr_test: test [':=' test]
 test: or_test ['if' or_test 'else' test] | lambdef
 or_test: and_test ('or' and_test)*
 and_test: not_test ('and' not_test)*
@@ -111,8 +112,8 @@
        '{' [dictsetmaker] '}' |
        '`' testlist1 '`' |
        NAME | NUMBER | STRING+ | '.' '.' '.')
-listmaker: (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] )
-testlist_gexp: (test|star_expr) ( comp_for | (',' (test|star_expr))* [','] )
+listmaker: (namedexpr_test|star_expr) ( comp_for | (',' (namedexpr_test|star_expr))* [','] )
+testlist_gexp: (namedexpr_test|star_expr) ( comp_for | (',' (namedexpr_test|star_expr))* [','] )
 lambdef: 'lambda' [varargslist] ':' test
 trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
 subscriptlist: subscript (',' subscript)* [',']
@@ -137,6 +138,7 @@
 # multiple (test comp_for) arguments are blocked; keyword unpackings
 # that precede iterable unpackings are blocked; etc.
 argument: ( test [comp_for] |
+            test ':=' test |
             test '=' test |
             '**' test |
 	        '*' test )
diff --git a/Lib/lib2to3/pgen2/grammar.py b/Lib/lib2to3/pgen2/grammar.py
index a1da546..6a4d575 100644
--- a/Lib/lib2to3/pgen2/grammar.py
+++ b/Lib/lib2to3/pgen2/grammar.py
@@ -178,6 +178,7 @@
 // DOUBLESLASH
 //= DOUBLESLASHEQUAL
 -> RARROW
+:= COLONEQUAL
 """
 
 opmap = {}
diff --git a/Lib/lib2to3/pgen2/token.py b/Lib/lib2to3/pgen2/token.py
index 1a67955..5f6612f 100755
--- a/Lib/lib2to3/pgen2/token.py
+++ b/Lib/lib2to3/pgen2/token.py
@@ -65,7 +65,8 @@
 AWAIT = 56
 ASYNC = 57
 ERRORTOKEN = 58
-N_TOKENS = 59
+COLONEQUAL = 59
+N_TOKENS = 60
 NT_OFFSET = 256
 #--end constants--
 
diff --git a/Lib/lib2to3/pgen2/tokenize.py b/Lib/lib2to3/pgen2/tokenize.py
index 7924ff3..0e2685d 100644
--- a/Lib/lib2to3/pgen2/tokenize.py
+++ b/Lib/lib2to3/pgen2/tokenize.py
@@ -93,7 +93,7 @@
                  r"~")
 
 Bracket = '[][(){}]'
-Special = group(r'\r?\n', r'[:;.,`@]')
+Special = group(r'\r?\n', r':=', r'[:;.,`@]')
 Funny = group(Operator, Bracket, Special)
 
 PlainToken = group(Number, Funny, String, Name)
diff --git a/Lib/lib2to3/tests/test_parser.py b/Lib/lib2to3/tests/test_parser.py
index a0c31e8..ba2bb78 100644
--- a/Lib/lib2to3/tests/test_parser.py
+++ b/Lib/lib2to3/tests/test_parser.py
@@ -629,6 +629,21 @@
         self.validate(s)
 
 
+class TestNamedAssignments(GrammarTest):
+
+    def test_named_assignment_if(self):
+        driver.parse_string("if f := x(): pass\n")
+
+    def test_named_assignment_while(self):
+        driver.parse_string("while f := x(): pass\n")
+
+    def test_named_assignment_generator(self):
+        driver.parse_string("any((lastNum := num) == 1 for num in [1, 2, 3])\n")
+
+    def test_named_assignment_listcomp(self):
+        driver.parse_string("[(lastNum := num) == 1 for num in [1, 2, 3]]\n")
+
+
 class TestPickleableException(unittest.TestCase):
     def test_ParseError(self):
         err = ParseError('msg', 2, None, (1, 'context'))
diff --git a/Misc/NEWS.d/next/Library/2019-06-18-19-38-27.bpo-36541.XI8mi1.rst b/Misc/NEWS.d/next/Library/2019-06-18-19-38-27.bpo-36541.XI8mi1.rst
new file mode 100644
index 0000000..e7b9dd6
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-06-18-19-38-27.bpo-36541.XI8mi1.rst
@@ -0,0 +1,2 @@
+lib2to3 now recognizes named assignment expressions (the walrus operator,
+``:=``)