diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -1652,7 +1652,8 @@
   if (!isAllowedIDChar(CodePoint, LangOpts)) {
     if (isASCII(CodePoint) || isUnicodeWhitespace(CodePoint))
       return false;
-    if (!isLexingRawMode())
+    if (!isLexingRawMode() && !ParsingPreprocessorDirective &&
+        !PP->isPreprocessedOutput())
       diagnoseInvalidUnicodeCodepointInIdentifier(
           PP->getDiagnostics(), LangOpts, CodePoint,
           makeCharRange(*this, CurPtr, UCNPtr),
@@ -1691,7 +1692,8 @@
     if (isASCII(CodePoint) || isUnicodeWhitespace(CodePoint))
       return false;
 
-    if (!isLexingRawMode())
+    if (!isLexingRawMode() && !ParsingPreprocessorDirective &&
+        !PP->isPreprocessedOutput())
       diagnoseInvalidUnicodeCodepointInIdentifier(
           PP->getDiagnostics(), LangOpts, CodePoint,
           makeCharRange(*this, CurPtr, UnicodePtr), /*IsFirst=*/false);
diff --git a/clang/test/Lexer/unicode.c b/clang/test/Lexer/unicode.c
--- a/clang/test/Lexer/unicode.c
+++ b/clang/test/Lexer/unicode.c
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -x c -std=c11 %s
 // RUN: %clang_cc1 -fsyntax-only -verify -x c++ -std=c++11 %s
+// RUN: %clang_cc1 -triple x86_64-scei-ps4 -E -DPP_ONLY=1 %s -o %t
 // RUN: %clang_cc1 -E -DPP_ONLY=1 %s -o %t
 // RUN: FileCheck --strict-whitespace --input-file=%t %s