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
@@ -1431,6 +1431,8 @@
 static bool isAllowedIDChar(uint32_t C, const LangOptions &LangOpts) {
   if (LangOpts.AsmPreprocessor) {
     return false;
+  } else if (LangOpts.DollarIdents && '$' == C) {
+    return true;
   } else if (LangOpts.CPlusPlus11 || LangOpts.C11) {
     static const llvm::sys::UnicodeCharSet C11AllowedIDChars(
         C11AllowedIDCharRanges);
diff --git a/clang/test/Preprocessor/ucn-pp-identifier.c b/clang/test/Preprocessor/ucn-pp-identifier.c
--- a/clang/test/Preprocessor/ucn-pp-identifier.c
+++ b/clang/test/Preprocessor/ucn-pp-identifier.c
@@ -28,8 +28,7 @@
 #define \U10000000  // expected-error {{macro name must be an identifier}}
 #define \u0061  // expected-error {{character 'a' cannot be specified by a universal character name}} expected-error {{macro name must be an identifier}}
 
-// FIXME: Not clear what our behavior should be here; \u0024 is "$".
-#define a\u0024  // expected-warning {{whitespace}}
+#define a\u0024
 
 #if \u0110 // expected-warning {{is not defined, evaluates to 0}}
 #endif