diff --git a/libc/Android.bp b/libc/Android.bp
index ecabb06..1e2458a 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -932,6 +932,21 @@
                 "arch-riscv64/bionic/setjmp.S",
                 "arch-riscv64/bionic/syscall.S",
                 "arch-riscv64/bionic/vfork.S",
+
+                "arch-riscv64/string/memchr_vext.S",
+                "arch-riscv64/string/memcmp_vext.S",
+                "arch-riscv64/string/memcpy_vext.S",
+                "arch-riscv64/string/memmove_vext.S",
+                "arch-riscv64/string/memset_vext.S",
+                "arch-riscv64/string/strcat_vext.S",
+                "arch-riscv64/string/strchr_vext.S",
+                "arch-riscv64/string/strcmp_vext.S",
+                "arch-riscv64/string/strcpy_vext.S",
+                "arch-riscv64/string/strlen_vext.S",
+                "arch-riscv64/string/strncat_vext.S",
+                "arch-riscv64/string/strncmp_vext.S",
+                "arch-riscv64/string/strncpy_vext.S",
+                "arch-riscv64/string/strnlen_vext.S",
             ],
         },
 
@@ -1541,6 +1556,9 @@
         arm64: {
             srcs: ["arch-arm64/static_function_dispatch.S"],
         },
+        riscv64: {
+            srcs: ["arch-riscv64/static_function_dispatch.S"]
+        },
     },
 }
 
@@ -1569,6 +1587,9 @@
         arm64: {
             srcs: ["arch-arm64/dynamic_function_dispatch.cpp"],
         },
+        riscv64: {
+            srcs: ["arch-riscv64/dynamic_function_dispatch.cpp"]
+        },
     },
 }
 
diff --git a/libc/NOTICE b/libc/NOTICE
index 4d3a108..441e79c 100644
--- a/libc/NOTICE
+++ b/libc/NOTICE
@@ -4540,6 +4540,34 @@
 
 -------------------------------------------------------------------
 
+Copyright (c) 2023 SiFive, Inc.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+3. The name of the company may not be used to endorse or promote
+   products derived from this software without specific prior written
+   permission.
+
+THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+-------------------------------------------------------------------
+
 Copyright (c)1999 Citrus Project,
 All rights reserved.
 
diff --git a/libc/arch-riscv64/dynamic_function_dispatch.cpp b/libc/arch-riscv64/dynamic_function_dispatch.cpp
new file mode 100644
index 0000000..0925c5f
--- /dev/null
+++ b/libc/arch-riscv64/dynamic_function_dispatch.cpp
@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <private/bionic_ifuncs.h>
+#include <stddef.h>
+#include <sys/auxv.h>
+
+#if defined(__riscv_v)
+extern "C" {
+
+typedef void* memchr_func(const void*, int, size_t);
+DEFINE_IFUNC_FOR(memchr) {
+  RETURN_FUNC(memchr_func, memchr_vext);
+}
+
+typedef int memcmp_func(const void*, const void*, size_t);
+DEFINE_IFUNC_FOR(memcmp) {
+  RETURN_FUNC(memcmp_func, memcmp_vext);
+}
+
+typedef void* memcpy_func(void*, const void*, size_t);
+DEFINE_IFUNC_FOR(memcpy) {
+  RETURN_FUNC(memcpy_func, memcpy_vext);
+}
+
+typedef void* memmove_func(void*, const void*, size_t);
+DEFINE_IFUNC_FOR(memmove) {
+  RETURN_FUNC(memmove_func, memmove_vext);
+}
+
+typedef void* memset_func(void*, int, size_t);
+DEFINE_IFUNC_FOR(memset) {
+  RETURN_FUNC(memset_func, memset_vext);
+}
+
+typedef char* strcat_func(char*, const char*);
+DEFINE_IFUNC_FOR(strcat) {
+  RETURN_FUNC(strcat_func, strcat_vext);
+}
+
+typedef char* strchr_func(const char*, int);
+DEFINE_IFUNC_FOR(strchr) {
+  RETURN_FUNC(strchr_func, strchr_vext);
+}
+
+typedef int strcmp_func(const char*, const char*);
+DEFINE_IFUNC_FOR(strcmp) {
+  RETURN_FUNC(strcmp_func, strcmp_vext);
+}
+
+typedef char* strcpy_func(char*, const char*);
+DEFINE_IFUNC_FOR(strcpy) {
+  RETURN_FUNC(strcpy_func, strcpy_vext);
+}
+
+typedef size_t strlen_func(const char*);
+DEFINE_IFUNC_FOR(strlen) {
+  RETURN_FUNC(strlen_func, strlen_vext);
+}
+
+typedef char* strncat_func(char*, const char*, size_t);
+DEFINE_IFUNC_FOR(strncat) {
+  RETURN_FUNC(strncat_func, strncat_vext);
+}
+
+typedef int strncmp_func(const char*, const char*, size_t);
+DEFINE_IFUNC_FOR(strncmp) {
+  RETURN_FUNC(strncmp_func, strncmp_vext);
+}
+
+typedef char* strncpy_func(char*, const char*, size_t);
+DEFINE_IFUNC_FOR(strncpy) {
+  RETURN_FUNC(strncpy_func, strncpy_vext);
+}
+
+typedef size_t strnlen_func(const char*, size_t);
+DEFINE_IFUNC_FOR(strnlen) {
+  RETURN_FUNC(strnlen_func, strnlen_vext);
+}
+
+}  // extern "C"
+#endif
diff --git a/libc/arch-riscv64/static_function_dispatch.S b/libc/arch-riscv64/static_function_dispatch.S
new file mode 100644
index 0000000..3bf0275
--- /dev/null
+++ b/libc/arch-riscv64/static_function_dispatch.S
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <private/bionic_asm.h>
+
+#define FUNCTION_DELEGATE(name, impl) \
+ENTRY(name); \
+    j impl; \
+END(name)
+
+#if defined(__riscv_v)
+
+FUNCTION_DELEGATE(memchr, memchr_vext)
+FUNCTION_DELEGATE(memcmp, memcmp_vext)
+FUNCTION_DELEGATE(memcpy, memcpy_vext)
+FUNCTION_DELEGATE(memmove, memmove_vext)
+FUNCTION_DELEGATE(memset, memset_vext)
+FUNCTION_DELEGATE(strcat, strcat_vext)
+FUNCTION_DELEGATE(strchr, strchr_vext)
+FUNCTION_DELEGATE(strcmp, strcmp_vext)
+FUNCTION_DELEGATE(strcpy, strcpy_vext)
+FUNCTION_DELEGATE(strlen, strlen_vext)
+FUNCTION_DELEGATE(strncat, strncat_vext)
+FUNCTION_DELEGATE(strncmp, strncmp_vext)
+FUNCTION_DELEGATE(strncpy, strncpy_vext)
+FUNCTION_DELEGATE(strnlen, strnlen_vext)
+
+#endif
+
+NOTE_GNU_PROPERTY()
diff --git a/libc/arch-riscv64/string/memchr_vext.S b/libc/arch-riscv64/string/memchr_vext.S
new file mode 100644
index 0000000..3761265
--- /dev/null
+++ b/libc/arch-riscv64/string/memchr_vext.S
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define iResult a0
+
+#define pSrc a0
+#define iValue a1
+#define iNum a2
+
+#define iVL a3
+#define iTemp a4
+
+#define ELEM_LMUL_SETTING m8
+#define vData v0
+#define vMask v8
+
+ENTRY(memchr_vext)
+
+L(loop):
+    vsetvli iVL, iNum, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8ff.v vData, (pSrc)
+    vmseq.vx vMask, vData, iValue
+    vfirst.m iTemp, vMask
+
+    # skip the loop if we find the matched value.
+    bgez iTemp, L(found)
+
+    csrr iVL, vl
+    sub iNum, iNum, iVL
+    add pSrc, pSrc, iVL
+
+    bnez iNum, L(loop)
+
+    li iResult, 0
+    ret
+
+L(found):
+    add iResult, pSrc, iTemp
+    ret
+
+END(memchr_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/memcmp_vext.S b/libc/arch-riscv64/string/memcmp_vext.S
new file mode 100644
index 0000000..d8e7a06
--- /dev/null
+++ b/libc/arch-riscv64/string/memcmp_vext.S
@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define iResult a0
+
+#define pSrc1 a0
+#define pSrc2 a1
+#define iNum a2
+
+#define iVL a3
+#define iTemp a4
+#define iTemp1 a5
+#define iTemp2 a6
+
+#define ELEM_LMUL_SETTING m8
+#define vData1 v0
+#define vData2 v8
+#define vMask v16
+
+ENTRY(memcmp_vext)
+
+L(loop):
+    vsetvli iVL, iNum, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8.v vData1, (pSrc1)
+    vle8.v vData2, (pSrc2)
+
+    vmsne.vv vMask, vData1, vData2
+    sub iNum, iNum, iVL
+    vfirst.m iTemp, vMask
+
+    /* skip the loop if we find the different
+       value between pSrc1 and pSrc2.  */
+    bgez iTemp, L(found)
+
+    add pSrc1, pSrc1, iVL
+    add pSrc2, pSrc2, iVL
+
+    bnez iNum, L(loop)
+
+    li iResult, 0
+    ret
+
+L(found):
+    add pSrc1, pSrc1, iTemp
+    add pSrc2, pSrc2, iTemp
+    lbu iTemp1, 0(pSrc1)
+    lbu iTemp2, 0(pSrc2)
+    sub iResult, iTemp1, iTemp2
+    ret
+
+END(memcmp_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/memcpy_vext.S b/libc/arch-riscv64/string/memcpy_vext.S
new file mode 100644
index 0000000..100f538
--- /dev/null
+++ b/libc/arch-riscv64/string/memcpy_vext.S
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pDst a0
+#define pSrc a1
+#define iNum a2
+
+#define iVL a3
+#define pDstPtr a4
+
+#define ELEM_LMUL_SETTING m8
+#define vData v0
+
+ENTRY(memcpy_vext)
+
+    mv pDstPtr, pDst
+
+L(loop):
+    vsetvli iVL, iNum, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8.v vData, (pSrc)
+    sub iNum, iNum, iVL
+    add pSrc, pSrc, iVL
+    vse8.v vData, (pDstPtr)
+    add pDstPtr, pDstPtr, iVL
+
+    bnez iNum, L(loop)
+
+    ret
+
+END(memcpy_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/memmove_vext.S b/libc/arch-riscv64/string/memmove_vext.S
new file mode 100644
index 0000000..722ffd1
--- /dev/null
+++ b/libc/arch-riscv64/string/memmove_vext.S
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pDst a0
+#define pSrc a1
+#define iNum a2
+
+#define iVL a3
+#define pDstPtr a4
+#define pSrcBackwardPtr a5
+#define pDstBackwardPtr a6
+
+#define ELEM_LMUL_SETTING m8
+#define vData v0
+
+ENTRY(memmove_vext)
+
+    mv pDstPtr, pDst
+
+    bgeu pSrc, pDst, L(forward_copy_loop)
+    add pSrcBackwardPtr, pSrc, iNum
+    add pDstBackwardPtr, pDst, iNum
+    bltu pDst, pSrcBackwardPtr, L(backward_copy_loop)
+
+L(forward_copy_loop):
+    vsetvli iVL, iNum, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8.v vData, (pSrc)
+    sub iNum, iNum, iVL
+    add pSrc, pSrc, iVL
+    vse8.v vData, (pDstPtr)
+    add pDstPtr, pDstPtr, iVL
+
+    bnez iNum, L(forward_copy_loop)
+    ret
+
+L(backward_copy_loop):
+    vsetvli iVL, iNum, e8, ELEM_LMUL_SETTING, ta, ma
+
+    sub pSrcBackwardPtr, pSrcBackwardPtr, iVL
+    vle8.v vData, (pSrcBackwardPtr)
+    sub iNum, iNum, iVL
+    sub pDstBackwardPtr, pDstBackwardPtr, iVL
+    vse8.v vData, (pDstBackwardPtr)
+    bnez iNum, L(backward_copy_loop)
+    ret
+
+END(memmove_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/memset_vext.S b/libc/arch-riscv64/string/memset_vext.S
new file mode 100644
index 0000000..ef8387d
--- /dev/null
+++ b/libc/arch-riscv64/string/memset_vext.S
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pDst a0
+#define iValue a1
+#define iNum a2
+
+#define iVL a3
+#define iTemp a4
+#define pDstPtr a5
+
+#define ELEM_LMUL_SETTING m8
+#define vData v0
+
+ENTRY(memset_vext)
+
+    mv pDstPtr, pDst
+
+    vsetvli iVL, iNum, e8, ELEM_LMUL_SETTING, ta, ma
+    vmv.v.x vData, iValue
+
+L(loop):
+    vse8.v vData, (pDstPtr)
+    sub iNum, iNum, iVL
+    add pDstPtr, pDstPtr, iVL
+    vsetvli iVL, iNum, e8, ELEM_LMUL_SETTING, ta, ma
+    bnez iNum, L(loop)
+
+    ret
+
+END(memset_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/strcat_vext.S b/libc/arch-riscv64/string/strcat_vext.S
new file mode 100644
index 0000000..790c07a
--- /dev/null
+++ b/libc/arch-riscv64/string/strcat_vext.S
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pDst a0
+#define pSrc a1
+#define pDstPtr a2
+
+#define iVL a3
+#define iCurrentVL a4
+#define iActiveElemPos a5
+
+#define ELEM_LMUL_SETTING m1
+#define vMask1 v0
+#define vMask2 v1
+#define vStr1 v8
+#define vStr2 v16
+
+ENTRY(strcat_vext)
+
+    mv pDstPtr, pDst
+
+    // the strlen of dst
+L(strlen_loop):
+    vsetvli iVL, zero, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8ff.v vStr1, (pDstPtr)
+    // find the '\0'
+    vmseq.vx vMask1, vStr1, zero
+    csrr iCurrentVL, vl
+    vfirst.m iActiveElemPos, vMask1
+    add pDstPtr, pDstPtr, iCurrentVL
+    bltz iActiveElemPos, L(strlen_loop)
+
+    sub pDstPtr, pDstPtr, iCurrentVL
+    add pDstPtr, pDstPtr, iActiveElemPos
+
+    // copy pSrc to pDstPtr
+L(strcpy_loop):
+    vsetvli iVL, zero, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8ff.v vStr1, (pSrc)
+    vmseq.vx vMask2, vStr1, zero
+    csrr iCurrentVL, vl
+    vfirst.m iActiveElemPos, vMask2
+    vmsif.m vMask1, vMask2
+    add pSrc, pSrc, iCurrentVL
+    vse8.v vStr1, (pDstPtr), vMask1.t
+    add pDstPtr, pDstPtr, iCurrentVL
+    bltz iActiveElemPos, L(strcpy_loop)
+
+    ret
+
+END(strcat_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/strchr_vext.S b/libc/arch-riscv64/string/strchr_vext.S
new file mode 100644
index 0000000..89828ea
--- /dev/null
+++ b/libc/arch-riscv64/string/strchr_vext.S
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pStr a0
+#define iCh a1
+#define iEndOffset a2
+#define iChOffset a3
+#define iTemp1 a4
+#define iTemp2 a5
+#define iCurrentVL a6
+#define iVL t0
+
+#define ELEM_LMUL_SETTING m1
+#define vStr v0
+#define vMaskEnd v8
+#define vMaskCh v9
+
+ENTRY(strchr_vext)
+
+L(strchr_loop):
+    vsetvli iVL, zero, e8, ELEM_LMUL_SETTING, ta, ma
+    vle8ff.v vStr, (pStr)
+    vmseq.vi vMaskEnd, vStr, 0
+    vmseq.vx vMaskCh, vStr, iCh
+    vfirst.m iEndOffset, vMaskEnd /* first occurrence of \0 */
+    vfirst.m iChOffset, vMaskCh /* first occurrence of ch */
+    sltz iTemp1, iChOffset
+    sltu iTemp2, iEndOffset, iChOffset
+    or iTemp1, iTemp1, iTemp2
+    beqz iTemp1, L(found_ch) /* Found ch, not preceded by \0? */
+    csrr iCurrentVL, vl
+    add pStr, pStr, iCurrentVL
+    bltz iEndOffset, L(strchr_loop) /* Didn't find \0? */
+    li pStr, 0
+    ret
+L(found_ch):
+    add pStr, pStr, iChOffset
+    ret
+
+END(strchr_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/strcmp_vext.S b/libc/arch-riscv64/string/strcmp_vext.S
new file mode 100644
index 0000000..d6ad96e
--- /dev/null
+++ b/libc/arch-riscv64/string/strcmp_vext.S
@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define iResult a0
+
+#define pStr1 a0
+#define pStr2 a1
+
+#define iVL a2
+#define iTemp1 a3
+#define iTemp2 a4
+#define iLMUL1 a5
+#define iLMUL2 a6
+#define iLMUL4 a7
+
+#define iLMUL t0
+
+#define vStr1 v0
+#define vStr2 v8
+#define vMask1 v16
+#define vMask2 v17
+
+ENTRY(strcmp_vext)
+
+    # increase the lmul using the following sequences:
+    # 1/2, 1/2, 1, 2, 4, 4, 4, ...
+
+    # lmul=1/2
+    vsetvli iVL, zero, e8, mf2, ta, ma
+
+    vle8ff.v vStr1, (pStr1)
+     # check if vStr1[i] == 0
+    vmseq.vx vMask1, vStr1, zero
+
+    vle8ff.v vStr2, (pStr2)
+    # check if vStr1[i] != vStr2[i]
+    vmsne.vv vMask2, vStr1, vStr2
+
+    # find the index x for vStr1[x]==0
+    vfirst.m iTemp1, vMask1
+    # find the index x for vStr1[x]!=vStr2[x]
+    vfirst.m iTemp2, vMask2
+
+    bgez iTemp1, L(check1)
+    bgez iTemp2, L(check2)
+
+    # get the current vl updated by vle8ff.
+    csrr iVL, vl
+    add pStr1, pStr1, iVL
+    add pStr2, pStr2, iVL
+
+    vsetvli iVL, zero, e8, mf2, ta, ma
+    addi iLMUL1, zero, 1
+    addi iLMUL, zero, 1
+    j L(loop)
+L(m1):
+    vsetvli iVL, zero, e8, m1, ta, ma
+    addi iLMUL2, zero, 2
+    addi iLMUL, zero, 2
+    j L(loop)
+L(m2):
+    vsetvli iVL, zero, e8, m2, ta, ma
+    addi iLMUL4, zero, 4
+    addi iLMUL, zero, 4
+    j L(loop)
+L(m4):
+    vsetvli iVL, zero, e8, m4, ta, ma
+
+L(loop):
+    vle8ff.v vStr1, (pStr1)
+    vmseq.vx vMask1, vStr1, zero
+
+    vle8ff.v vStr2, (pStr2)
+    vmsne.vv vMask2, vStr1, vStr2
+
+    vfirst.m iTemp1, vMask1
+    vfirst.m iTemp2, vMask2
+
+    bgez iTemp1, L(check1)
+    bgez iTemp2, L(check2)
+
+    csrr iVL, vl
+    add pStr1, pStr1, iVL
+    add pStr2, pStr2, iVL
+
+    beq iLMUL, iLMUL1, L(m1)
+    beq iLMUL, iLMUL2, L(m2)
+    beq iLMUL, iLMUL4, L(m4)
+    j L(loop)
+
+    // iTemp1>=0
+L(check1):
+    bltz iTemp2, 1f
+    blt iTemp2, iTemp1, L(check2)
+1:
+    // iTemp2<0
+    // iTemp2>=0 && iTemp1<iTemp2
+    add pStr1, pStr1, iTemp1
+    add pStr2, pStr2, iTemp1
+    lbu iTemp1, 0(pStr1)
+    lbu iTemp2, 0(pStr2)
+    sub iResult, iTemp1, iTemp2
+    ret
+
+    // iTemp1<0
+    // iTemp2>=0
+L(check2):
+    add pStr1, pStr1, iTemp2
+    add pStr2, pStr2, iTemp2
+    lbu iTemp1, 0(pStr1)
+    lbu iTemp2, 0(pStr2)
+    sub iResult, iTemp1, iTemp2
+    ret
+
+END(strcmp_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/strcpy_vext.S b/libc/arch-riscv64/string/strcpy_vext.S
new file mode 100644
index 0000000..9c11f7d
--- /dev/null
+++ b/libc/arch-riscv64/string/strcpy_vext.S
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pDst a0
+#define pSrc a1
+#define pDstPtr a2
+
+#define iVL a3
+#define iCurrentVL a4
+#define iActiveElemPos a5
+
+#define ELEM_LMUL_SETTING m1
+#define vMask1 v0
+#define vMask2 v1
+#define vStr1 v8
+#define vStr2 v16
+
+ENTRY(strcpy_vext)
+
+    mv pDstPtr, pDst
+
+    // copy pSrc to pDstPtr
+L(strcpy_loop):
+    vsetvli iVL, zero, e8, ELEM_LMUL_SETTING, ta, ma
+    vle8ff.v vStr1, (pSrc)
+    vmseq.vx vMask2, vStr1, zero
+    csrr iCurrentVL, vl
+    vfirst.m iActiveElemPos, vMask2
+    vmsif.m vMask1, vMask2
+    add pSrc, pSrc, iCurrentVL
+    vse8.v vStr1, (pDstPtr), vMask1.t
+    add pDstPtr, pDstPtr, iCurrentVL
+    bltz iActiveElemPos, L(strcpy_loop)
+
+    ret
+
+END(strcpy_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/strlen_vext.S b/libc/arch-riscv64/string/strlen_vext.S
new file mode 100644
index 0000000..393af58
--- /dev/null
+++ b/libc/arch-riscv64/string/strlen_vext.S
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define iResult a0
+#define pStr a0
+#define pCopyStr a1
+#define iVL a2
+#define iCurrentVL a2
+#define iEndOffset a3
+
+#define ELEM_LMUL_SETTING m2
+#define vStr v0
+#define vMaskEnd v2
+
+ENTRY(strlen_vext)
+
+    mv pCopyStr, pStr
+L(loop):
+    vsetvli iVL, zero, e8, ELEM_LMUL_SETTING, ta, ma
+    vle8ff.v vStr, (pCopyStr)
+    csrr iCurrentVL, vl
+    vmseq.vi vMaskEnd, vStr, 0
+    vfirst.m iEndOffset, vMaskEnd
+    add pCopyStr, pCopyStr, iCurrentVL
+    bltz iEndOffset, L(loop)
+
+    add pStr, pStr, iCurrentVL
+    add pCopyStr, pCopyStr, iEndOffset
+    sub iResult, pCopyStr, iResult
+
+    ret
+
+END(strlen)
+
+#endif
diff --git a/libc/arch-riscv64/string/strncat_vext.S b/libc/arch-riscv64/string/strncat_vext.S
new file mode 100644
index 0000000..e9da434
--- /dev/null
+++ b/libc/arch-riscv64/string/strncat_vext.S
@@ -0,0 +1,121 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pDst a0
+#define pSrc a1
+#define iLength a2
+#define pDstPtr a3
+
+#define iVL a4
+#define iCurrentVL a5
+#define iActiveElemPos a6
+
+#define ELEM_LMUL_SETTING m1
+#define vMask1 v0
+#define vMask2 v1
+#define vStr1 v8
+#define vStr2 v16
+
+ENTRY(strncat_vext)
+
+    mv pDstPtr, pDst
+
+    // the strlen of dst
+L(strlen_loop):
+    vsetvli iVL, zero, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8ff.v vStr1, (pDstPtr)
+    // find the '\0'
+    vmseq.vx vMask1, vStr1, zero
+    csrr iCurrentVL, vl
+    vfirst.m iActiveElemPos, vMask1
+    add pDstPtr, pDstPtr, iCurrentVL
+    bltz iActiveElemPos, L(strlen_loop)
+
+    sub pDstPtr, pDstPtr, iCurrentVL
+    add pDstPtr, pDstPtr, iActiveElemPos
+
+    // copy pSrc to pDstPtr
+L(strcpy_loop):
+    vsetvli iVL, iLength, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8ff.v vStr1, (pSrc)
+    vmseq.vx vMask2, vStr1, zero
+    csrr iCurrentVL, vl
+    vfirst.m iActiveElemPos, vMask2
+    vmsif.m vMask1, vMask2
+    add pSrc, pSrc, iCurrentVL
+    sub iLength, iLength, iCurrentVL
+    vse8.v vStr1, (pDstPtr), vMask1.t
+    add pDstPtr, pDstPtr, iCurrentVL
+    beqz iLength, L(fill_zero)
+    bltz iActiveElemPos, L(strcpy_loop)
+
+    ret
+
+L(fill_zero):
+    bgez iActiveElemPos, L(fill_zero_end)
+    sb zero, (pDstPtr)
+
+L(fill_zero_end):
+    ret
+
+END(strncat_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/strncmp_vext.S b/libc/arch-riscv64/string/strncmp_vext.S
new file mode 100644
index 0000000..88f0f3e
--- /dev/null
+++ b/libc/arch-riscv64/string/strncmp_vext.S
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define iResult a0
+
+#define pStr1 a0
+#define pStr2 a1
+#define iLength a2
+
+#define iVL a3
+#define iTemp1 a4
+#define iTemp2 a5
+
+#define ELEM_LMUL_SETTING m1
+#define vStr1 v0
+#define vStr2 v4
+#define vMask1 v8
+#define vMask2 v9
+
+ENTRY(strncmp_vext)
+
+    beqz iLength, L(zero_length)
+
+L(loop):
+    vsetvli iVL, iLength, e8, ELEM_LMUL_SETTING, ta, ma
+
+    vle8ff.v vStr1, (pStr1)
+     # vStr1[i] == 0
+    vmseq.vx vMask1, vStr1, zero
+
+    vle8ff.v vStr2, (pStr2)
+    # vStr1[i] != vStr2[i]
+    vmsne.vv vMask2, vStr1, vStr2
+
+    csrr iVL, vl
+
+    # r = mask1 | mask2
+    # We could use vfirst.m to get the first zero char or the
+    # first different char between str1 and str2.
+    vmor.mm vMask1, vMask1, vMask2
+
+    sub iLength, iLength, iVL
+
+    vfirst.m iTemp1, vMask1
+
+    bgez iTemp1, L(end_loop)
+
+    add pStr1, pStr1, iVL
+    add pStr2, pStr2, iVL
+    bnez iLength, L(loop)
+L(end_loop):
+
+    add pStr1, pStr1, iTemp1
+    add pStr2, pStr2, iTemp1
+    lbu iTemp1, 0(pStr1)
+    lbu iTemp2, 0(pStr2)
+
+    sub iResult, iTemp1, iTemp2
+    ret
+
+L(zero_length):
+    li iResult, 0
+    ret
+
+END(strncmp_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/strncpy_vext.S b/libc/arch-riscv64/string/strncpy_vext.S
new file mode 100644
index 0000000..1aedaf9
--- /dev/null
+++ b/libc/arch-riscv64/string/strncpy_vext.S
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pDst a0
+#define pSrc a1
+#define iLength a2
+#define pDstPtr a3
+
+#define iVL a4
+#define iCurrentVL a5
+#define iActiveElemPos a6
+
+#define ELEM_LMUL_SETTING m1
+#define vMask1 v0
+#define vMask2 v1
+#define ZERO_FILL_ELEM_LMUL_SETTING m8
+#define vStr1 v8
+#define vStr2 v16
+
+ENTRY(strncpy_vext)
+
+    mv pDstPtr, pDst
+
+    // copy pSrc to pDstPtr
+L(strcpy_loop):
+    vsetvli iVL, iLength, e8, ELEM_LMUL_SETTING, ta, ma
+    vle8ff.v vStr1, (pSrc)
+    vmseq.vx vMask2, vStr1, zero
+    csrr iCurrentVL, vl
+    vfirst.m iActiveElemPos, vMask2
+    vmsif.m vMask1, vMask2
+    add pSrc, pSrc, iCurrentVL
+    sub iLength, iLength, iCurrentVL
+    vse8.v vStr1, (pDstPtr), vMask1.t
+    add pDstPtr, pDstPtr, iCurrentVL
+    bgez iActiveElemPos, L(fill_zero)
+    bnez iLength, L(strcpy_loop)
+    ret
+
+    # fill the tail zero.
+L(fill_zero):
+    sub iVL, iCurrentVL, iActiveElemPos
+    add iLength, iLength, iVL
+    bnez iLength, 1f
+    ret
+1:
+    sub pDstPtr, pDstPtr, iVL
+    vsetvli zero, iLength, e8, ZERO_FILL_ELEM_LMUL_SETTING, ta, ma
+    vmv.v.x vStr2, zero
+
+L(fill_zero_loop):
+    vsetvli iVL, iLength, e8, ZERO_FILL_ELEM_LMUL_SETTING, ta, ma
+    vse8.v vStr2, (pDstPtr)
+    sub iLength, iLength, iVL
+    add pDstPtr, pDstPtr, iVL
+    bnez iLength, L(fill_zero_loop)
+
+    ret
+
+END(strncpy_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/strnlen_vext.S b/libc/arch-riscv64/string/strnlen_vext.S
new file mode 100644
index 0000000..f546689
--- /dev/null
+++ b/libc/arch-riscv64/string/strnlen_vext.S
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#if defined(__riscv_v)
+
+#include "sys/asm.h"
+
+#define pStr a0
+#define pCopyStr a2
+#define iRetValue a0
+#define iMaxlen a1
+#define iCurrentVL a3
+#define iEndOffset a4
+
+#define ELEM_LMUL_SETTING m1
+#define vStr v0
+#define vMaskEnd v8
+
+ENTRY(strnlen_vext)
+
+    mv pCopyStr, pStr
+    mv iRetValue, iMaxlen
+L(strnlen_loop):
+    beqz iMaxlen, L(end_strnlen_loop)
+    vsetvli zero, iMaxlen, e8, ELEM_LMUL_SETTING, ta, ma
+    vle8ff.v vStr, (pCopyStr)
+    vmseq.vi vMaskEnd, vStr, 0
+    vfirst.m iEndOffset, vMaskEnd /* first occurrence of \0 */
+    csrr iCurrentVL, vl
+    add pCopyStr, pCopyStr, iCurrentVL
+    sub iMaxlen, iMaxlen, iCurrentVL
+    bltz iEndOffset, L(strnlen_loop)
+    add iMaxlen, iMaxlen, iCurrentVL
+    sub iRetValue, iRetValue, iMaxlen
+    add iRetValue, iRetValue, iEndOffset
+L(end_strnlen_loop):
+    ret
+
+END(strnlen_vext)
+
+#endif
diff --git a/libc/arch-riscv64/string/sys/asm.h b/libc/arch-riscv64/string/sys/asm.h
new file mode 100644
index 0000000..cc76dc5
--- /dev/null
+++ b/libc/arch-riscv64/string/sys/asm.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+/*
+ * Copyright (c) 2023 SiFive, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY SIFIVE INC ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL SIFIVE INC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _SYS_ASM_H
+#define _SYS_ASM_H
+
+#undef LEAF
+#define LEAF(symbol)       \
+  .globl symbol;           \
+  .align 2;                \
+  .type symbol, @function; \
+  symbol:                  \
+  .cfi_startproc;
+
+#undef END
+#define END(function) \
+  .cfi_endproc;       \
+  .size function, .- function
+
+#define ENTRY(name) LEAF(name)
+
+#define L(label) .L##label
+
+#endif /* _SYS_ASM_H */
diff --git a/libc/include/bits/fortify/poll.h b/libc/include/bits/fortify/poll.h
index 0b5cd4b..f2e27d7 100644
--- a/libc/include/bits/fortify/poll.h
+++ b/libc/include/bits/fortify/poll.h
@@ -30,9 +30,9 @@
 #error "Never include this file directly; instead, include <poll.h>"
 #endif
 
-int __poll_chk(struct pollfd*, nfds_t, int, size_t) __INTRODUCED_IN(23);
-int __ppoll_chk(struct pollfd*, nfds_t, const struct timespec*, const sigset_t*, size_t) __INTRODUCED_IN(23);
-int __ppoll64_chk(struct pollfd*, nfds_t, const struct timespec*, const sigset64_t*, size_t) __INTRODUCED_IN(28);
+int __poll_chk(struct pollfd* _Nullable, nfds_t, int, size_t) __INTRODUCED_IN(23);
+int __ppoll_chk(struct pollfd* _Nullable, nfds_t, const struct timespec* _Nullable, const sigset_t* _Nullable, size_t) __INTRODUCED_IN(23);
+int __ppoll64_chk(struct pollfd* _Nullable, nfds_t, const struct timespec* _Nullable, const sigset64_t* _Nullable, size_t) __INTRODUCED_IN(28);
 
 #if defined(__BIONIC_FORTIFY)
 #define __bos_fd_count_trivially_safe(bos_val, fds, fd_count)              \
@@ -40,7 +40,7 @@
                                (fd_count) <= __BIONIC_CAST(static_cast, nfds_t, -1) / sizeof(*fds))
 
 __BIONIC_FORTIFY_INLINE
-int poll(struct pollfd* const fds __pass_object_size, nfds_t fd_count, int timeout)
+int poll(struct pollfd* _Nullable const fds __pass_object_size, nfds_t fd_count, int timeout)
     __overloadable
     __clang_error_if(__bos_unevaluated_lt(__bos(fds), sizeof(*fds) * fd_count),
                      "in call to 'poll', fd_count is larger than the given buffer") {
@@ -55,7 +55,7 @@
 }
 
 __BIONIC_FORTIFY_INLINE
-int ppoll(struct pollfd* const fds __pass_object_size, nfds_t fd_count, const struct timespec* timeout, const sigset_t* mask)
+int ppoll(struct pollfd* _Nullable const fds __pass_object_size, nfds_t fd_count, const struct timespec* _Nullable timeout, const sigset_t* _Nullable mask)
     __overloadable
     __clang_error_if(__bos_unevaluated_lt(__bos(fds), sizeof(*fds) * fd_count),
                      "in call to 'ppoll', fd_count is larger than the given buffer") {
@@ -71,7 +71,7 @@
 
 #if __ANDROID_API__ >= 28
 __BIONIC_FORTIFY_INLINE
-int ppoll64(struct pollfd* const fds __pass_object_size, nfds_t fd_count, const struct timespec* timeout, const sigset64_t* mask)
+int ppoll64(struct pollfd* _Nullable const fds __pass_object_size, nfds_t fd_count, const struct timespec* _Nullable timeout, const sigset64_t* _Nullable mask)
     __overloadable
     __clang_error_if(__bos_unevaluated_lt(__bos(fds), sizeof(*fds) * fd_count),
                      "in call to 'ppoll64', fd_count is larger than the given buffer") {
diff --git a/libc/include/bits/threads_inlines.h b/libc/include/bits/threads_inlines.h
index 17de4a1..5878e0a 100644
--- a/libc/include/bits/threads_inlines.h
+++ b/libc/include/bits/threads_inlines.h
@@ -48,46 +48,46 @@
   }
 }
 
-__BIONIC_THREADS_INLINE void call_once(once_flag* __flag,
-                                       void (*__function)(void)) {
+__BIONIC_THREADS_INLINE void call_once(once_flag* _Nonnull __flag,
+                                       void (* _Nonnull __function)(void)) {
   pthread_once(__flag, __function);
 }
 
 
 
-__BIONIC_THREADS_INLINE int cnd_broadcast(cnd_t* __cnd) {
+__BIONIC_THREADS_INLINE int cnd_broadcast(cnd_t* _Nonnull __cnd) {
   return __bionic_thrd_error(pthread_cond_broadcast(__cnd));
 }
 
-__BIONIC_THREADS_INLINE void cnd_destroy(cnd_t* __cnd) {
+__BIONIC_THREADS_INLINE void cnd_destroy(cnd_t* _Nonnull __cnd) {
   pthread_cond_destroy(__cnd);
 }
 
-__BIONIC_THREADS_INLINE int cnd_init(cnd_t* __cnd) {
+__BIONIC_THREADS_INLINE int cnd_init(cnd_t* _Nonnull __cnd) {
   return __bionic_thrd_error(pthread_cond_init(__cnd, NULL));
 }
 
-__BIONIC_THREADS_INLINE int cnd_signal(cnd_t* __cnd) {
+__BIONIC_THREADS_INLINE int cnd_signal(cnd_t* _Nonnull __cnd) {
   return __bionic_thrd_error(pthread_cond_signal(__cnd));
 }
 
-__BIONIC_THREADS_INLINE int cnd_timedwait(cnd_t* __cnd,
-                                          mtx_t* __mtx,
-                                          const struct timespec* __timeout) {
+__BIONIC_THREADS_INLINE int cnd_timedwait(cnd_t* _Nonnull __cnd,
+                                          mtx_t* _Nonnull __mtx,
+                                          const struct timespec* _Nullable __timeout) {
   return __bionic_thrd_error(pthread_cond_timedwait(__cnd, __mtx, __timeout));
 }
 
-__BIONIC_THREADS_INLINE int cnd_wait(cnd_t* __cnd, mtx_t* __mtx) {
+__BIONIC_THREADS_INLINE int cnd_wait(cnd_t* _Nonnull __cnd, mtx_t* _Nonnull __mtx) {
   return __bionic_thrd_error(pthread_cond_wait(__cnd, __mtx));
 }
 
 
 
-__BIONIC_THREADS_INLINE void mtx_destroy(mtx_t* __mtx) {
+__BIONIC_THREADS_INLINE void mtx_destroy(mtx_t* _Nonnull __mtx) {
   pthread_mutex_destroy(__mtx);
 }
 
-__BIONIC_THREADS_INLINE int mtx_init(mtx_t* __mtx, int __type) {
+__BIONIC_THREADS_INLINE int mtx_init(mtx_t* _Nonnull __mtx, int __type) {
   int __pthread_type = (__type & mtx_recursive) ? PTHREAD_MUTEX_RECURSIVE
                                                 : PTHREAD_MUTEX_NORMAL;
   __type &= ~mtx_recursive;
@@ -99,31 +99,32 @@
   return __bionic_thrd_error(pthread_mutex_init(__mtx, &__attr));
 }
 
-__BIONIC_THREADS_INLINE int mtx_lock(mtx_t* __mtx) {
+__BIONIC_THREADS_INLINE int mtx_lock(mtx_t* _Nonnull __mtx) {
   return __bionic_thrd_error(pthread_mutex_lock(__mtx));
 }
 
-__BIONIC_THREADS_INLINE int mtx_timedlock(mtx_t* __mtx,
-                                          const struct timespec* __timeout) {
+__BIONIC_THREADS_INLINE int mtx_timedlock(mtx_t* _Nonnull __mtx,
+                                          const struct timespec* _Nullable __timeout) {
   return __bionic_thrd_error(pthread_mutex_timedlock(__mtx, __timeout));
 }
 
-__BIONIC_THREADS_INLINE int mtx_trylock(mtx_t* __mtx) {
+__BIONIC_THREADS_INLINE int mtx_trylock(mtx_t* _Nonnull __mtx) {
   return __bionic_thrd_error(pthread_mutex_trylock(__mtx));
 }
 
-__BIONIC_THREADS_INLINE int mtx_unlock(mtx_t* __mtx) {
+__BIONIC_THREADS_INLINE int mtx_unlock(mtx_t* _Nonnull __mtx) {
   return __bionic_thrd_error(pthread_mutex_unlock(__mtx));
 }
 
-
-
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnullability-completeness"
 struct __bionic_thrd_data {
   thrd_start_t __func;
   void* __arg;
 };
+#pragma clang diagnostic pop
 
-static inline void* __bionic_thrd_trampoline(void* __arg) {
+static inline void* _Nonnull __bionic_thrd_trampoline(void* _Nonnull __arg) {
   struct __bionic_thrd_data __data =
       *__BIONIC_CAST(static_cast, struct __bionic_thrd_data*, __arg);
   free(__arg);
@@ -132,9 +133,9 @@
                        __BIONIC_CAST(static_cast, uintptr_t, __result));
 }
 
-__BIONIC_THREADS_INLINE int thrd_create(thrd_t* __thrd,
-                                        thrd_start_t __func,
-                                        void* __arg) {
+__BIONIC_THREADS_INLINE int thrd_create(thrd_t* _Nonnull __thrd,
+                                        thrd_start_t _Nonnull __func,
+                                        void* _Nullable __arg) {
   struct __bionic_thrd_data* __pthread_arg =
       __BIONIC_CAST(static_cast, struct __bionic_thrd_data*,
                     malloc(sizeof(struct __bionic_thrd_data)));
@@ -164,7 +165,7 @@
                              __BIONIC_CAST(static_cast, uintptr_t, __result)));
 }
 
-__BIONIC_THREADS_INLINE int thrd_join(thrd_t __thrd, int* __result) {
+__BIONIC_THREADS_INLINE int thrd_join(thrd_t __thrd, int* _Nullable __result) {
   void* __pthread_result;
   if (pthread_join(__thrd, &__pthread_result) != 0) return thrd_error;
   if (__result) {
@@ -173,8 +174,8 @@
   return thrd_success;
 }
 
-__BIONIC_THREADS_INLINE int thrd_sleep(const struct timespec* __duration,
-                                       struct timespec* __remaining) {
+__BIONIC_THREADS_INLINE int thrd_sleep(const struct timespec* _Nonnull __duration,
+                                       struct timespec* _Nullable __remaining) {
   int __rc = nanosleep(__duration, __remaining);
   if (__rc == 0) return 0;
   return (errno == EINTR) ? -1 : -2;
@@ -186,7 +187,7 @@
 
 
 
-__BIONIC_THREADS_INLINE int tss_create(tss_t* __key, tss_dtor_t __dtor) {
+__BIONIC_THREADS_INLINE int tss_create(tss_t* _Nonnull __key, tss_dtor_t _Nullable __dtor) {
   return __bionic_thrd_error(pthread_key_create(__key, __dtor));
 }
 
@@ -194,11 +195,11 @@
   pthread_key_delete(__key);
 }
 
-__BIONIC_THREADS_INLINE void* tss_get(tss_t __key) {
+__BIONIC_THREADS_INLINE void* _Nullable tss_get(tss_t __key) {
   return pthread_getspecific(__key);
 }
 
-__BIONIC_THREADS_INLINE int tss_set(tss_t __key, void* __value) {
+__BIONIC_THREADS_INLINE int tss_set(tss_t __key, void* _Nonnull __value) {
   return __bionic_thrd_error(pthread_setspecific(__key, __value));
 }
 
diff --git a/libc/stdio/scanf_common.h b/libc/stdio/scanf_common.h
new file mode 100644
index 0000000..8132e90
--- /dev/null
+++ b/libc/stdio/scanf_common.h
@@ -0,0 +1,115 @@
+/*	$OpenBSD: vfscanf.c,v 1.31 2014/03/19 05:17:01 guenther Exp $ */
+/*-
+ * Copyright (c) 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <ctype.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <locale.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+#include <wctype.h>
+#include "local.h"
+
+#include <platform/bionic/macros.h>
+#include <private/bionic_fortify.h>
+#include <private/bionic_mbstate.h>
+
+#define BUF 513 /* Maximum length of numeric string. */
+
+// Flags used during conversion.
+// Size/type:
+#define LONG 0x00001        // l: long or double
+#define LONGDBL 0x00002     // L: long double
+#define SHORT 0x00004       // h: short
+#define SHORTSHORT 0x00008  // hh: 8 bit integer
+#define LLONG 0x00010       // ll: long long (+ deprecated q: quad)
+#define POINTER 0x00020     // p: void* (as hex)
+#define SIZEINT 0x00040     // z: (signed) size_t
+#define MAXINT 0x00080      // j: intmax_t
+#define PTRINT 0x00100      // t: ptrdiff_t
+#define NOSKIP 0x00200      // [ or c: do not skip blanks
+// Modifiers:
+#define SUPPRESS 0x00400  // *: suppress assignment
+#define UNSIGNED 0x00800  // %[oupxX] conversions
+#define ALLOCATE 0x01000  // m: allocate a char*
+// Internal use during integer parsing:
+#define SIGNOK 0x02000    // +/- is (still) legal
+#define HAVESIGN 0x04000  // Sign detected
+#define NDIGITS 0x08000   // No digits detected
+#define PFXOK 0x10000     // "0x" prefix is (still) legal
+#define PFBOK 0x20000     // "0b" prefix is (still) legal
+#define NZDIGITS 0x40000  // No zero digits detected
+
+// Conversion types.
+#define CT_CHAR 0    // %c conversion
+#define CT_CCL 1     // %[...] conversion
+#define CT_STRING 2  // %s conversion
+#define CT_INT 3     // Integer: strtoimax/strtoumax
+#define CT_FLOAT 4   // Float: strtod
+
+#define to_digit(c) static_cast<int>((c) - '0')
+#define is_digit(c) ((unsigned)to_digit(c) <= 9)
+
+// Append a digit to a value and check for overflow.
+#define APPEND_DIGIT(val, dig)               \
+  do {                                       \
+    if ((val) > INT_MAX / 10)                \
+      errno = ENOMEM;                        \
+    else {                                   \
+      (val) *= 10;                           \
+      if ((val) > INT_MAX - to_digit((dig))) \
+        errno = ENOMEM;                      \
+      else                                   \
+        (val) += to_digit((dig));            \
+    }                                        \
+  } while (0)
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-function"
+// Trasnlate a fixed size integer argument for the %w/%wf format to a
+// flag representation. Supported sizes are 8, 16, 32, and 64 so far.
+// See details in bionic/libc/include/stdint.h
+static int w_to_flag(int size, bool fast) {
+  static constexpr int fast_size = sizeof(void*) == 8 ? LLONG : 0;
+  if (size == 8) return SHORTSHORT;
+  if (size == 16) return fast ? fast_size : SHORT;
+  if (size == 32) return fast ? fast_size : 0;
+  if (size == 64) return LLONG;
+  __fortify_fatal("%%w%s%d is unsupported", fast ? "f" : "", size);
+}
+
+#pragma clang diagnostic pop
\ No newline at end of file
diff --git a/libc/stdio/vfscanf.cpp b/libc/stdio/vfscanf.cpp
index dfd001d..65f54a5 100644
--- a/libc/stdio/vfscanf.cpp
+++ b/libc/stdio/vfscanf.cpp
@@ -31,53 +31,7 @@
  * SUCH DAMAGE.
  */
 
-#include <ctype.h>
-#include <inttypes.h>
-#include <stdarg.h>
-#include <stddef.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/param.h>
-#include <wctype.h>
-#include "local.h"
-
-#include <private/bionic_fortify.h>
-#include <platform/bionic/macros.h>
-#include <private/bionic_mbstate.h>
-
-#define BUF 513 /* Maximum length of numeric string. */
-
-// Flags used during conversion.
-// Size/type:
-#define LONG       0x00001 // l: long or double
-#define LONGDBL    0x00002 // L: long double
-#define SHORT      0x00004 // h: short
-#define SHORTSHORT 0x00008 // hh: 8 bit integer
-#define LLONG      0x00010 // ll: long long (+ deprecated q: quad)
-#define POINTER    0x00020 // p: void* (as hex)
-#define SIZEINT    0x00040 // z: (signed) size_t
-#define MAXINT     0x00080 // j: intmax_t
-#define PTRINT     0x00100 // t: ptrdiff_t
-#define NOSKIP     0x00200 // [ or c: do not skip blanks
-// Modifiers:
-#define SUPPRESS   0x00400 // *: suppress assignment
-#define UNSIGNED   0x00800 // %[oupxX] conversions
-#define ALLOCATE   0x01000 // m: allocate a char*
-// Internal use during integer parsing:
-#define SIGNOK     0x02000 // +/- is (still) legal
-#define HAVESIGN   0x04000 // Sign detected
-#define NDIGITS    0x08000 // No digits detected
-#define PFXOK      0x10000 // "0x" prefix is (still) legal
-#define PFBOK      0x20000 // "0b" prefix is (still) legal
-#define NZDIGITS   0x40000 // No zero digits detected
-
-// Conversion types.
-#define CT_CHAR 0   // %c conversion
-#define CT_CCL 1    // %[...] conversion
-#define CT_STRING 2 // %s conversion
-#define CT_INT 3    // Integer: strtoimax/strtoumax
-#define CT_FLOAT 4  // Float: strtod
+#include "scanf_common.h"
 
 static const unsigned char* __sccl(char*, const unsigned char*);
 
@@ -122,6 +76,7 @@
      */
 again:
     c = *fmt++;
+reswitch:
     switch (c) {
       case '%':
 literal:
@@ -220,6 +175,18 @@
         base = 10;
         break;
 
+      case 'w': {
+        int size = 0;
+        bool fast = false;
+        c = *fmt++;
+        while (is_digit(c)) {
+          APPEND_DIGIT(size, c);
+          c = *fmt++;
+        }
+        flags |= w_to_flag(size, fast);
+        goto reswitch;
+      }
+
       case 'X':
       case 'x':
         flags |= PFXOK; /* enable 0x prefixing */
diff --git a/libc/stdio/vfwscanf.cpp b/libc/stdio/vfwscanf.cpp
index 5f21acd..14b1754 100644
--- a/libc/stdio/vfwscanf.cpp
+++ b/libc/stdio/vfwscanf.cpp
@@ -31,62 +31,7 @@
  * SUCH DAMAGE.
  */
 
-#include <inttypes.h>
-#include <limits.h>
-#include <locale.h>
-#include <stdarg.h>
-#include <stddef.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <wctype.h>
-#include "local.h"
-
-#include <platform/bionic/macros.h>
-
-#define BUF 513 /* Maximum length of numeric string. */
-
-/*
- * Flags used during conversion.
- */
-#define LONG 0x00001       /* l: long or double */
-#define LONGDBL 0x00002    /* L: long double */
-#define SHORT 0x00004      /* h: short */
-#define SHORTSHORT 0x00008 /* hh: 8 bit integer */
-#define LLONG 0x00010      /* ll: long long (+ deprecated q: quad) */
-#define POINTER 0x00020    /* p: void * (as hex) */
-#define SIZEINT 0x00040    /* z: (signed) size_t */
-#define MAXINT 0x00080     /* j: intmax_t */
-#define PTRINT 0x00100     /* t: ptrdiff_t */
-#define NOSKIP 0x00200     /* [ or c: do not skip blanks */
-#define SUPPRESS 0x00400   /* *: suppress assignment */
-#define UNSIGNED 0x00800   /* %[oupxX] conversions */
-
-/*
- * The following are used in numeric conversions only:
- * SIGNOK, HAVESIGN, NDIGITS, DPTOK, and EXPOK are for floating point;
- * SIGNOK, HAVESIGN, NDIGITS, PFXOK, and NZDIGITS are for integral.
- */
-#define SIGNOK   0x01000  /* +/- is (still) legal */
-#define HAVESIGN 0x02000 /* sign detected */
-#define NDIGITS  0x04000 /* no digits detected */
-
-#define DPTOK    0x08000 /* (float) decimal point is still legal */
-#define EXPOK    0x10000 /* (float) exponent (e+3, etc) still legal */
-
-#define PFBOK    0x20000 /* 0x prefix is (still) legal */
-#define PFXOK    0x40000 /* 0x prefix is (still) legal */
-#define NZDIGITS 0x80000 /* no zero digits detected */
-
-/*
- * Conversion types.
- */
-#define CT_CHAR 0   /* %c conversion */
-#define CT_CCL 1    /* %[...] conversion */
-#define CT_STRING 2 /* %s conversion */
-#define CT_INT 3    /* integer, i.e., strtoimax or strtoumax */
-#define CT_FLOAT 4  /* floating, i.e., strtod */
-
+#include "scanf_common.h"
 // An interpretive version of __sccl from vfscanf.c --- a table of all wchar_t values would
 // be a little too expensive, and some kind of compressed version isn't worth the trouble.
 static inline bool in_ccl(wchar_t wc, const wchar_t* ccl) {
@@ -176,6 +121,7 @@
      */
   again:
     c = *fmt++;
+  reswitch:
     switch (c) {
       case '%':
       literal:
@@ -273,6 +219,18 @@
         base = 10;
         break;
 
+      case 'w': {
+        int size = 0;
+        bool fast = false;
+        c = *fmt++;
+        while (is_digit(c)) {
+          APPEND_DIGIT(size, c);
+          c = *fmt++;
+        }
+        flags |= w_to_flag(size, fast);
+        goto reswitch;
+      }
+
       case 'X':
       case 'x':
         flags |= PFXOK; /* enable 0x prefixing */
diff --git a/tests/stdio_test.cpp b/tests/stdio_test.cpp
index b85edfb..c20597b 100644
--- a/tests/stdio_test.cpp
+++ b/tests/stdio_test.cpp
@@ -3486,3 +3486,141 @@
   GTEST_SKIP() << "no %w in glibc";
 #endif
 }
+
+TEST(STDIO_TEST, sscanf_w_base) {
+#if defined(__BIONIC__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wformat-invalid-specifier"
+  int8_t a;
+  EXPECT_EQ(1, sscanf("<0b101>", "<%w8b>", &a));
+  EXPECT_EQ(0b101, a);
+  int8_t b1;
+  EXPECT_EQ(1, sscanf("<0xFF>", "<%w8i>", &b1));
+  EXPECT_EQ(-1, b1);
+  int8_t b2;
+  EXPECT_EQ(1, sscanf("<0x1FF>", "<%w8i>", &b2));
+  EXPECT_EQ(-1, b2);
+  int16_t c1;
+  EXPECT_EQ(1, sscanf("<0xFFFF>", "<%w16i>", &c1));
+  EXPECT_EQ(-1, c1);
+  uint16_t c2;
+  EXPECT_EQ(1, sscanf("<64>", "<%w16d>", &c2));
+  EXPECT_EQ(64, c2);
+  int32_t d;
+  EXPECT_EQ(1, sscanf("<021>", "<%w32o>", &d));
+  EXPECT_EQ(021, d);
+  uint32_t e;
+  EXPECT_EQ(1, sscanf("<-1>", "<%w32u>", &e));
+  EXPECT_EQ(4294967295, e);
+  int64_t f;
+  EXPECT_EQ(1, sscanf("<0x3b>", "<%w64x>", &f));
+  EXPECT_EQ(0x3b, f);
+  EXPECT_EQ(1, sscanf("<0x3b>", "<%w64X>", &f));
+  EXPECT_EQ(0x3B, f);
+#pragma clang diagnostic pop
+#else
+  GTEST_SKIP() << "no %w in glibc";
+#endif
+}
+
+TEST(STDIO_TEST, sscanf_w_combination) {
+#if defined(__BIONIC__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wformat"
+#pragma clang diagnostic ignored "-Wformat-invalid-specifier"
+#pragma clang diagnostic ignored "-Wformat-extra-args"
+  uint32_t a;
+  int64_t b;
+  char c;
+
+  EXPECT_EQ(3, sscanf("<0b10101010101010101010101010101010 0x3333333344444444 1>",
+                      "<%w32b %w64x %c>", &a, &b, &c));
+  EXPECT_EQ(0xaaaaaaaa, a);
+  EXPECT_EQ(0x3333333344444444, b);
+  EXPECT_EQ('1', c);
+#pragma clang diagnostic pop
+#else
+  GTEST_SKIP() << "no %w in glibc";
+#endif
+}
+
+TEST(STDIO_TEST, sscanf_invalid_w_width) {
+#if defined(__BIONIC__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wformat-invalid-specifier"
+  int32_t a;
+  EXPECT_DEATH(sscanf("<100>", "<%w20d>", &a), "%w20 is unsupported");
+#pragma clang diagnostic pop
+#else
+  GTEST_SKIP() << "no %w in glibc";
+#endif
+}
+
+TEST(STDIO_TEST, swscanf_w_base) {
+#if defined(__BIONIC__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wformat-invalid-specifier"
+  int8_t a;
+  EXPECT_EQ(1, swscanf(L"<0b101>", L"<%w8b>", &a));
+  EXPECT_EQ(0b101, a);
+  int8_t b1;
+  EXPECT_EQ(1, swscanf(L"<0xFF>", L"<%w8i>", &b1));
+  EXPECT_EQ(-1, b1);
+  int8_t b2;
+  EXPECT_EQ(1, swscanf(L"<0x1FF>", L"<%w8i>", &b2));
+  EXPECT_EQ(-1, b2);
+  int16_t c1;
+  EXPECT_EQ(1, swscanf(L"<0xFFFF>", L"<%w16i>", &c1));
+  EXPECT_EQ(-1, c1);
+  uint16_t c2;
+  EXPECT_EQ(1, swscanf(L"<64>", L"<%w16d>", &c2));
+  EXPECT_EQ(64, c2);
+  int32_t d;
+  EXPECT_EQ(1, swscanf(L"<021>", L"<%w32o>", &d));
+  EXPECT_EQ(021, d);
+  uint32_t e;
+  EXPECT_EQ(1, swscanf(L"<-1>", L"<%w32u>", &e));
+  EXPECT_EQ(4294967295, e);
+  int64_t f;
+  EXPECT_EQ(1, swscanf(L"<0x3b>", L"<%w64x>", &f));
+  EXPECT_EQ(0x3b, f);
+  EXPECT_EQ(1, swscanf(L"<0x3b>", L"<%w64X>", &f));
+  EXPECT_EQ(0x3B, f);
+#pragma clang diagnostic pop
+#else
+  GTEST_SKIP() << "no %w in glibc";
+#endif
+}
+
+TEST(STDIO_TEST, swscanf_w_combination) {
+#if defined(__BIONIC__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wformat"
+#pragma clang diagnostic ignored "-Wformat-invalid-specifier"
+#pragma clang diagnostic ignored "-Wformat-extra-args"
+  uint32_t a;
+  int64_t b;
+  char c;
+
+  EXPECT_EQ(3, swscanf(L"<0b10101010101010101010101010101010 0x3333333344444444 1>",
+                       L"<%w32b %w64x %c>", &a, &b, &c));
+  EXPECT_EQ(0xaaaaaaaa, a);
+  EXPECT_EQ(0x3333333344444444, b);
+  EXPECT_EQ('1', c);
+#pragma clang diagnostic pop
+#else
+  GTEST_SKIP() << "no %w in glibc";
+#endif
+}
+
+TEST(STDIO_TEST, swscanf_invalid_w_width) {
+#if defined(__BIONIC__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wformat-invalid-specifier"
+  int32_t a;
+  EXPECT_DEATH(swscanf(L"<100>", L"<%w20d>", &a), "%w20 is unsupported");
+#pragma clang diagnostic pop
+#else
+  GTEST_SKIP() << "no %w in glibc";
+#endif
+}
\ No newline at end of file