diff --git a/Include/Python.h b/Include/Python.h
index 1feb153..c7514d3 100644
--- a/Include/Python.h
+++ b/Include/Python.h
@@ -53,6 +53,15 @@
 #include "pyport.h"
 #include "pymacro.h"
 
+/* A convenient way for code to know if clang's memory sanitizer is enabled. */
+#if defined(__has_feature)
+#  if __has_feature(memory_sanitizer)
+#    if !defined(MEMORY_SANITIZER)
+#      define MEMORY_SANITIZER
+#    endif
+#  endif
+#endif
+
 #include "pyatomic.h"
 
 /* Debug-mode build with pymalloc implies PYMALLOC_DEBUG.