diff --git a/sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S b/sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S
index 6506ce6252..cd7a32c7c2 100644
--- a/sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S
+++ b/sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S
@@ -29,12 +29,16 @@
 	.section .text.avx512,"ax",@progbits
 #if defined PIC
 ENTRY (MEMSET_CHK)
-	cmpq	%rdx, %rcx
+	cmp	%RDX_LP, %RCX_LP
 	jb	HIDDEN_JUMPTARGET (__chk_fail)
 END (MEMSET_CHK)
 #endif
 
 ENTRY (MEMSET)
+# ifdef __ILP32__
+	/* Clear the upper 32 bits.  */
+	mov	%edx, %edx
+# endif
 	vpxor	%xmm0, %xmm0, %xmm0
 	vmovd	%esi, %xmm1
 	lea	(%rdi, %rdx), %rsi
diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
index 71a0887c68..5e0d307d85 100644
--- a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
@@ -75,8 +75,8 @@
 	.section SECTION(.text),"ax",@progbits
 #if VEC_SIZE == 16 && IS_IN (libc)
 ENTRY (__bzero)
-	movq	%rdi, %rax /* Set return value.  */
-	movq	%rsi, %rdx /* Set n.  */
+	mov	%RDI_LP, %RAX_LP /* Set return value.  */
+	mov	%RSI_LP, %RDX_LP /* Set n.  */
 	pxor	%xmm0, %xmm0
 	jmp	L(entry_from_bzero)
 END (__bzero)
@@ -86,13 +86,13 @@ weak_alias (__bzero, bzero)
 #if IS_IN (libc)
 # if defined SHARED
 ENTRY_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))
-	cmpq	%rdx, %rcx
+	cmp	%RDX_LP, %RCX_LP
 	jb	HIDDEN_JUMPTARGET (__chk_fail)
 END_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))
 # endif
 
 ENTRY (WMEMSET_SYMBOL (__wmemset, unaligned))
-	shlq	$2, %rdx
+	shl	$2, %RDX_LP
 	WMEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)
 	jmp	L(entry_from_bzero)
 END (WMEMSET_SYMBOL (__wmemset, unaligned))
@@ -100,13 +100,17 @@ END (WMEMSET_SYMBOL (__wmemset, unaligned))
 
 #if defined SHARED && IS_IN (libc)
 ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))
-	cmpq	%rdx, %rcx
+	cmp	%RDX_LP, %RCX_LP
 	jb	HIDDEN_JUMPTARGET (__chk_fail)
 END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))
 #endif
 
 ENTRY (MEMSET_SYMBOL (__memset, unaligned))
 	MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)
+# ifdef __ILP32__
+	/* Clear the upper 32 bits.  */
+	mov	%edx, %edx
+# endif
 L(entry_from_bzero):
 	cmpq	$VEC_SIZE, %rdx
 	jb	L(less_vec)
@@ -122,14 +126,14 @@ END (MEMSET_SYMBOL (__memset, unaligned))
 
 # if VEC_SIZE == 16
 ENTRY (__memset_chk_erms)
-	cmpq	%rdx, %rcx
+	cmp	%RDX_LP, %RCX_LP
 	jb	HIDDEN_JUMPTARGET (__chk_fail)
 END (__memset_chk_erms)
 
 /* Only used to measure performance of REP STOSB.  */
 ENTRY (__memset_erms)
 	/* Skip zero length.  */
-	testq	%rdx, %rdx
+	test	%RDX_LP, %RDX_LP
 	jnz	 L(stosb)
 	movq	%rdi, %rax
 	ret
@@ -141,11 +145,11 @@ ENTRY (MEMSET_SYMBOL (__memset, erms))
 L(stosb):
 	/* Issue vzeroupper before rep stosb.  */
 	VZEROUPPER
-	movq	%rdx, %rcx
+	mov	%RDX_LP, %RCX_LP
 	movzbl	%sil, %eax
-	movq	%rdi, %rdx
+	mov	%RDI_LP, %RDX_LP
 	rep stosb
-	movq	%rdx, %rax
+	mov	%RDX_LP, %RAX_LP
 	ret
 # if VEC_SIZE == 16
 END (__memset_erms)
@@ -155,16 +159,20 @@ END (MEMSET_SYMBOL (__memset, erms))
 
 # if defined SHARED && IS_IN (libc)
 ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
-	cmpq	%rdx, %rcx
+	cmp	%RDX_LP, %RCX_LP
 	jb	HIDDEN_JUMPTARGET (__chk_fail)
 END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))
 # endif
 
 ENTRY (MEMSET_SYMBOL (__memset, unaligned_erms))
 	MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)
-	cmpq	$VEC_SIZE, %rdx
+# ifdef __ILP32__
+	/* Clear the upper 32 bits.  */
+	mov	%edx, %edx
+# endif
+	cmp	$VEC_SIZE, %RDX_LP
 	jb	L(less_vec)
-	cmpq	$(VEC_SIZE * 2), %rdx
+	cmp	$(VEC_SIZE * 2), %RDX_LP
 	ja	L(stosb_more_2x_vec)
 	/* From VEC and to 2 * VEC.  No branch when size == VEC_SIZE.  */
 	VMOVU	%VEC(0), -VEC_SIZE(%rdi,%rdx)
diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile
index e99dbd7c86..98bd9ae9cd 100644
--- a/sysdeps/x86_64/x32/Makefile
+++ b/sysdeps/x86_64/x32/Makefile
@@ -7,9 +7,9 @@ endif
 
 ifeq ($(subdir),string)
 tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy \
-	 tst-size_t-memrchr
+	 tst-size_t-memrchr tst-size_t-memset
 endif
 
 ifeq ($(subdir),wcsmbs)
-tests += tst-size_t-wmemchr tst-size_t-wmemcmp
+tests += tst-size_t-wmemchr tst-size_t-wmemcmp tst-size_t-wmemset
 endif
diff --git a/sysdeps/x86_64/x32/tst-size_t-memset.c b/sysdeps/x86_64/x32/tst-size_t-memset.c
new file mode 100644
index 0000000000..2c367af6cd
--- /dev/null
+++ b/sysdeps/x86_64/x32/tst-size_t-memset.c
@@ -0,0 +1,73 @@
+/* Test memset with size_t in the lower 32 bits of 64-bit register.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifdef WIDE
+# define TEST_NAME "wmemset"
+#else
+# define TEST_NAME "memset"
+#endif /* WIDE */
+
+#include "test-size_t.h"
+
+#ifdef WIDE
+# include <wchar.h>
+# define MEMSET wmemset
+# define CHAR wchar_t
+#else
+# define MEMSET memset
+# define CHAR char
+#endif /* WIDE */
+
+IMPL (MEMSET, 1)
+
+typedef CHAR *(*proto_t) (CHAR *, int, size_t);
+
+static void *
+__attribute__ ((noinline, noclone))
+do_memset (parameter_t a, parameter_t b)
+{
+  return CALL (&b, a.p, (uintptr_t) b.p, a.len);
+}
+
+static int
+test_main (void)
+{
+  test_init ();
+
+  CHAR ch = 0x23;
+  parameter_t src = { { page_size / sizeof (CHAR) }, buf2 };
+  parameter_t c = { { 0 }, (void *) (uintptr_t) ch };
+
+  int ret = 0;
+  FOR_EACH_IMPL (impl, 0)
+    {
+      c.fn = impl->fn;
+      CHAR *p = (CHAR *) do_memset (src, c);
+      size_t i;
+      for (i = 0; i < src.len; i++)
+	if (p[i] != ch)
+	  {
+	    error (0, 0, "Wrong result in function %s", impl->name);
+	    ret = 1;
+	  }
+    }
+
+  return ret ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/x86_64/x32/tst-size_t-wmemset.c b/sysdeps/x86_64/x32/tst-size_t-wmemset.c
new file mode 100644
index 0000000000..955eb488c2
--- /dev/null
+++ b/sysdeps/x86_64/x32/tst-size_t-wmemset.c
@@ -0,0 +1,20 @@
+/* Test wmemset with size_t in the lower 32 bits of 64-bit register.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#define WIDE 1
+#include "tst-size_t-memset.c"
