Index: clang/include/clang/Basic/DiagnosticLexKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticLexKinds.td
+++ clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -106,7 +106,7 @@
 
 def ext_multichar_character_literal : Warning<
   "multi-character character constant">, InGroup<MultiChar>;
-def ext_four_char_character_literal : Warning<
+def ext_four_char_character_literal : Remark<
   "multi-character character constant">, InGroup<FourByteMultiChar>;
 
 
Index: clang/test/CXX/lex/lex.literal/lex.ccon/p1.cpp
===================================================================
--- clang/test/CXX/lex/lex.literal/lex.ccon/p1.cpp
+++ clang/test/CXX/lex/lex.literal/lex.ccon/p1.cpp
@@ -1,12 +1,12 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
-// Expect the warning of the four-character character constant after changing it from extension to implementation-defined
+// expected-no-diagnostics
 
 // Check types of char literals
 extern char a;
 extern __typeof('a') a;
 extern int b;
-extern __typeof('asdf') b; // expected-warning {{multi-character character constant}}
+extern __typeof('asdf') b;
 extern wchar_t c;
 extern __typeof(L'a') c;
 #if __cplusplus >= 201103L
Index: clang/test/FixIt/format.m
===================================================================
--- clang/test/FixIt/format.m
+++ clang/test/FixIt/format.m
@@ -162,16 +162,13 @@
 
 
   NSLog(@"%s", 'abcd'); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}} \
-  // expected-warning {{multi-character character constant}}
-  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:11-[[@LINE-2]]:13}:"%d"
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:13}:"%d"
 
   NSLog(@"%lf", 'abcd'); // expected-warning{{format specifies type 'double' but the argument has type 'int'}} \
-  // expected-warning {{multi-character character constant}}
-  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:11-[[@LINE-2]]:14}:"%d"
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:14}:"%d"
 
   NSLog(@"%@", 'abcd'); // expected-warning{{format specifies type 'id' but the argument has type 'int'}} \
-  // expected-warning {{multi-character character constant}}
-  // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:11-[[@LINE-2]]:13}:"%d"
+  // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:13}:"%d"
 }
 
 void multichar_constants_false_negative() {
@@ -181,8 +178,7 @@
   // many C library functions like fgetc() actually return an int (using -1
   // as a sentinel).
   NSLog(@"%c", 'abcd'); // missing-warning{{format specifies type 'char' but the argument has type 'int'}} \
-  // expected-warning {{multi-character character constant}}
-  // CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-2]]:11-[[@LINE-2]]:13}:"%d"
+  // CHECK-NOT: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:13}:"%d"
 }
 
 
Index: clang/test/Lexer/char-literal.cpp
===================================================================
--- clang/test/Lexer/char-literal.cpp
+++ clang/test/Lexer/char-literal.cpp
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin -std=c++11 -Wfour-char-constants -fsyntax-only -verify %s
-// RUN: %clang_cc1 -triple x86_64-apple-darwin -std=c11 -x c -Wfour-char-constants -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -std=c++11 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -std=c11 -x c -fsyntax-only -verify %s
 
 #ifndef __cplusplus
 typedef __WCHAR_TYPE__ wchar_t;
@@ -9,7 +9,7 @@
 
 int a = 'ab'; // expected-warning {{multi-character character constant}}
 int b = '\xFF\xFF'; // expected-warning {{multi-character character constant}}
-int c = 'APPS'; // expected-warning {{multi-character character constant}}
+int c = 'APPS';
 
 char d = '鈱?; // expected-error {{character too large for enclosing character literal type}}
 char e = '\u2318'; // expected-error {{character too large for enclosing character literal type}}
Index: clang/test/Lexer/constants.c
===================================================================
--- clang/test/Lexer/constants.c
+++ clang/test/Lexer/constants.c
@@ -26,7 +26,7 @@
   '\\
 t',
   '??!',  // expected-warning {{trigraph converted to '|' character}}
-  'abcd'  // expected-warning {{multi-character character constant}}
+  'abcd'
 };
 
 //  PR4499
@@ -36,15 +36,16 @@
 int m3 = '\\\
 ';
 
+// The four-character character constants wouldn't cause warning anymore after we change it to "Remark"
 
 #pragma clang diagnostic ignored "-Wmultichar"
 
 int d = 'df'; // no warning.
-int e = 'abcd';  // still warn: expected-warning {{multi-character character constant}}
+int e = 'abcd';
 
-#pragma clang diagnostic ignored "-Wfour-char-constants"
+// #pragma clang diagnostic ignored "-Wfour-char-constants"
 
-int f = 'abcd';  // ignored.
+int f = 'abcd';
 
 // rdar://problem/6974641
 float t0[] = {
Index: clang/test/Lexer/multi-character-character-constant.c
===================================================================
--- clang/test/Lexer/multi-character-character-constant.c
+++ clang/test/Lexer/multi-character-character-constant.c
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -pedantic-errors %s
 
 int x = 'ab'; // expected-warning {{multi-character character constant}}
-int y = 'abcd'; // expected-warning {{multi-character character constant}}
+int y = 'abcd'; // no warning.
 
 int main() {
    return 0;
Index: clang/test/Preprocessor/expr_multichar.c
===================================================================
--- clang/test/Preprocessor/expr_multichar.c
+++ clang/test/Preprocessor/expr_multichar.c
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 < %s -E -verify -triple i686-pc-linux-gnu
-// Expect the warning of the four-character character constant after changing it from extension to implementation-defined
+// expected-no-diagnostics
 
-#if (('1234' >> 24) != '1') // expected-warning {{multi-character character constant}}
+#if (('1234' >> 24) != '1')
 #error Bad multichar constant calculation!
 #endif