diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
index c4428a176973311950429e0ba00c4ce13e9f6fe6..2622c0742c92d0e4a6b515d37c2a2f6b1a461758 100644
--- a/arch/x86/boot/string.c
+++ b/arch/x86/boot/string.c
@@ -34,6 +34,14 @@ int memcmp(const void *s1, const void *s2, size_t len)
 	return diff;
 }
 
+/*
+ * Clang may lower `memcmp == 0` to `bcmp == 0`.
+ */
+int bcmp(const void *s1, const void *s2, size_t len)
+{
+	return memcmp(s1, s2, len);
+}
+
 int strcmp(const char *str1, const char *str2)
 {
 	const unsigned char *s1 = (const unsigned char *)str1;
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 3d8144627b126b8e965c119c68030d9577c8392b..8901a1f89cf57bd16cbf79d6625a804274c6afe4 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -6,6 +6,9 @@ purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o string
 targets += $(purgatory-y)
 PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
 
+$(obj)/string.o: $(srctree)/arch/x86/boot/compressed/string.c FORCE
+	$(call if_changed_rule,cc_o_c)
+
 $(obj)/sha256.o: $(srctree)/lib/sha256.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
diff --git a/arch/x86/purgatory/purgatory.c b/arch/x86/purgatory/purgatory.c
index 025c34ac0d848f642a4b4b1c2c9577c52aa72614..7971f7a8af59f1aa84bec3e9ea2129c8b0c629ee 100644
--- a/arch/x86/purgatory/purgatory.c
+++ b/arch/x86/purgatory/purgatory.c
@@ -70,3 +70,9 @@ void purgatory(void)
 	}
 	copy_backup_region();
 }
+
+/*
+ * Defined in order to reuse memcpy() and memset() from
+ * arch/x86/boot/compressed/string.c
+ */
+void warn(const char *msg) {}
diff --git a/arch/x86/purgatory/string.c b/arch/x86/purgatory/string.c
deleted file mode 100644
index 795ca4f2cb3c912e37f214802cde76fc4fea7985..0000000000000000000000000000000000000000
--- a/arch/x86/purgatory/string.c
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * Simple string functions.
- *
- * Copyright (C) 2014 Red Hat Inc.
- *
- * Author:
- *       Vivek Goyal <vgoyal@redhat.com>
- *
- * This source code is licensed under the GNU General Public License,
- * Version 2.  See the file COPYING for more details.
- */
-
-#include <linux/types.h>
-
-#include "../boot/string.c"
-
-void *memcpy(void *dst, const void *src, size_t len)
-{
-	return __builtin_memcpy(dst, src, len);
-}
-
-void *memset(void *dst, int c, size_t len)
-{
-	return __builtin_memset(dst, c, len);
-}