diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index 0d99bf11d260..e4ce1cae03bf 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -616,6 +616,12 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
 	return false;
 }
 
+/*
+ * To work around what seems to be an optimizer bug, the macro arguments
+ * need to have const copies or the values end up changed by the time they
+ * reach fortify_warn_once(). See commit 6f7630b1b5bc ("fortify: Capture
+ * __bos() results in const temp vars") for more details.
+ */
 #define __fortify_memcpy_chk(p, q, size, p_size, q_size,		\
 			     p_size_field, q_size_field, op) ({		\
 	const size_t __fortify_size = (size_t)(size);			\
@@ -623,6 +629,8 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
 	const size_t __q_size = (q_size);				\
 	const size_t __p_size_field = (p_size_field);			\
 	const size_t __q_size_field = (q_size_field);			\
+	/* Keep a mutable version of the size for the final copy. */	\
+	size_t __copy_size = __fortify_size;				\
 	fortify_warn_once(fortify_memcpy_chk(__fortify_size, __p_size,	\
 				     __q_size, __p_size_field,		\
 				     __q_size_field, FORTIFY_FUNC_ ##op), \
@@ -630,7 +638,11 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
 		  __fortify_size,					\
 		  "field \"" #p "\" at " FILE_LINE,			\
 		  __p_size_field);					\
-	__underlying_##op(p, q, __fortify_size);			\
+	/* Hide only the run-time size from value range tracking to */	\
+	/* silence compile-time false positive bounds warnings. */	\
+	if (!__builtin_constant_p(__copy_size))				\
+		OPTIMIZER_HIDE_VAR(__copy_size);			\
+	__underlying_##op(p, q, __copy_size);				\
 })
 
 /*