diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index f2148a8..15cc21b 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -186,6 +186,16 @@
 #error "MBEDTLS_ENTROPY_FORCE_SHA256 defined, but not all prerequisites"
 #endif
 
+#if defined(__has_feature)
+#if __has_feature(memory_sanitizer)
+#define MBEDTLS_HAS_MEMSAN
+#endif
+#endif
+#if defined(MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN) &&  !defined(MBEDTLS_HAS_MEMSAN)
+#error "MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN requires building with MemorySanitizer"
+#endif
+#undef MBEDTLS_HAS_MEMSAN
+
 #if defined(MBEDTLS_TEST_NULL_ENTROPY) && \
     ( !defined(MBEDTLS_ENTROPY_C) || !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES) )
 #error "MBEDTLS_TEST_NULL_ENTROPY defined, but not all prerequisites"
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index e00c546..124c597 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -1907,6 +1907,19 @@
 //#define MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH
 
 /**
+ * \def MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN
+ *
+ * Enable testing of the constant-flow nature of some sensitive functions with
+ * clang's MemorySanitizer. This causes some existing tests to also test
+ * non-functional properties of the code under test.
+ *
+ * This setting requires compiling with clang -fsanitize=memory.
+ *
+ * Uncomment to enable testing of the constant-flow nature of seletected code.
+ */
+//#define MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN
+
+/**
  * \def MBEDTLS_TEST_HOOKS
  *
  * Enable features for invasive testing such as introspection functions and