Index: lib/Lex/PPMacroExpansion.cpp
===================================================================
--- lib/Lex/PPMacroExpansion.cpp
+++ lib/Lex/PPMacroExpansion.cpp
@@ -1133,6 +1133,7 @@
       .Case("enumerator_attributes", true)
       .Case("nullability", true)
       .Case("nullability_on_arrays", true)
+      .Case("leak_sanitizer", LangOpts.Sanitize.has(SanitizerKind::Leak))
       .Case("memory_sanitizer", LangOpts.Sanitize.has(SanitizerKind::Memory))
       .Case("thread_sanitizer", LangOpts.Sanitize.has(SanitizerKind::Thread))
       .Case("dataflow_sanitizer", LangOpts.Sanitize.has(SanitizerKind::DataFlow))
Index: test/Lexer/has_feature_leak_sanitizer.cpp
===================================================================
--- /dev/null
+++ test/Lexer/has_feature_leak_sanitizer.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -E -fsanitize=leak %s -o - | FileCheck --check-prefix=CHECK-LSAN %s
+// RUN: %clang_cc1 -E  %s -o - | FileCheck --check-prefix=CHECK-NO-LSAN %s
+
+#if __has_feature(leak_sanitizer)
+int LeakSanitizerEnabled();
+#else
+int LeakSanitizerDisabled();
+#endif
+
+// CHECK-LSAN: LeakSanitizerEnabled
+// CHECK-NO-LSAN: LeakSanitizerDisabled