Index: libc/config/linux/aarch64/entrypoints.txt
===================================================================
--- libc/config/linux/aarch64/entrypoints.txt
+++ libc/config/linux/aarch64/entrypoints.txt
@@ -64,6 +64,7 @@
     libc.src.string.strnlen
     libc.src.string.strpbrk
     libc.src.string.strrchr
+    libc.src.string.strsep
     libc.src.string.strsignal
     libc.src.string.strspn
     libc.src.string.strstr
Index: libc/config/linux/arm/entrypoints.txt
===================================================================
--- libc/config/linux/arm/entrypoints.txt
+++ libc/config/linux/arm/entrypoints.txt
@@ -51,6 +51,7 @@
     libc.src.string.strnlen
     libc.src.string.strpbrk
     libc.src.string.strrchr
+    libc.src.string.strsep
     libc.src.string.strspn
     libc.src.string.strstr
     libc.src.string.strtok
Index: libc/config/linux/riscv64/entrypoints.txt
===================================================================
--- libc/config/linux/riscv64/entrypoints.txt
+++ libc/config/linux/riscv64/entrypoints.txt
@@ -65,6 +65,7 @@
     libc.src.string.strnlen
     libc.src.string.strpbrk
     libc.src.string.strrchr
+    libc.src.string.strsep
     libc.src.string.strsignal
     libc.src.string.strspn
     libc.src.string.strstr
Index: libc/config/linux/x86_64/entrypoints.txt
===================================================================
--- libc/config/linux/x86_64/entrypoints.txt
+++ libc/config/linux/x86_64/entrypoints.txt
@@ -65,6 +65,7 @@
     libc.src.string.strnlen
     libc.src.string.strpbrk
     libc.src.string.strrchr
+    libc.src.string.strsep
     libc.src.string.strsignal
     libc.src.string.strspn
     libc.src.string.strstr
Index: libc/src/string/CMakeLists.txt
===================================================================
--- libc/src/string/CMakeLists.txt
+++ libc/src/string/CMakeLists.txt
@@ -315,6 +315,16 @@
     strrchr.h
 )
 
+add_entrypoint_object(
+  strsep
+  SRCS
+    strsep.cpp
+  HDRS
+    strsep.h
+  DEPENDS
+    .string_utils
+)
+
 add_entrypoint_object(
   strsignal
   SRCS
Index: libc/src/string/strsep.h
===================================================================
--- /dev/null
+++ libc/src/string/strsep.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for strsep ------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STRING_STRSEP_H
+#define LLVM_LIBC_SRC_STRING_STRSEP_H
+
+namespace __llvm_libc {
+
+char *strsep(char **stringp, const char *delim);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_STRSEP_H
Index: libc/src/string/strsep.cpp
===================================================================
--- /dev/null
+++ libc/src/string/strsep.cpp
@@ -0,0 +1,21 @@
+//===-- Implementation of strsep ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/string/strsep.h"
+
+#include "src/string/string_utils.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(char *, strsep, (char **stringp, const char *delim)) {
+  if (!*stringp)
+    return nullptr;
+  return internal::string_token(*stringp, delim, stringp);
+}
+
+} // namespace __llvm_libc
Index: libc/test/src/string/CMakeLists.txt
===================================================================
--- libc/test/src/string/CMakeLists.txt
+++ libc/test/src/string/CMakeLists.txt
@@ -298,6 +298,16 @@
     libc.src.string.strrchr
 )
 
+add_libc_unittest(
+  strsep_test
+  SUITE
+    libc_string_unittests
+  SRCS
+    strsep_test.cpp
+  DEPENDS
+    libc.src.string.strsep
+)
+
 add_libc_unittest(
   strsignal_test
   SUITE
Index: libc/test/src/string/strsep_test.cpp
===================================================================
--- /dev/null
+++ libc/test/src/string/strsep_test.cpp
@@ -0,0 +1,52 @@
+//===-- Unittests for strsep ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/string/strsep.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcStrsepTest, NullSrc) {
+  char *string = nullptr;
+  EXPECT_STREQ(__llvm_libc::strsep(&string, ""), nullptr);
+}
+
+TEST(LlvmLibcStrsepTest, NoTokenFound) {
+  {
+    char s[] = "";
+    char *string = s, *orig = s;
+    EXPECT_STREQ(__llvm_libc::strsep(&string, ""), nullptr);
+    EXPECT_EQ(orig, string);
+  }
+  {
+    char s[] = "abcde";
+    char *string = s, *orig = s;
+    EXPECT_STREQ(__llvm_libc::strsep(&string, ""), orig);
+    EXPECT_EQ(string, orig + 5);
+  }
+  {
+    char s[] = "abcde";
+    char *string = s, *orig = s;
+    EXPECT_STREQ(__llvm_libc::strsep(&string, "fghijk"), orig);
+    EXPECT_EQ(string, orig + 5);
+  }
+}
+
+TEST(LlvmLibcStrsepTest, TokenFound) {
+  char s[] = "abacd";
+  char *string = s;
+  EXPECT_STREQ(__llvm_libc::strsep(&string, "c"), "aba");
+  EXPECT_STREQ(string, "d");
+}
+
+TEST(LlvmLibcStrsepTest, DelimitersShouldNotBeIncludedInToken) {
+  char s[] = "__ab__:_cd__:__ef__:__";
+  char *string = s;
+  ASSERT_STREQ(__llvm_libc::strsep(&string, "_:"), "ab");
+  ASSERT_STREQ(__llvm_libc::strsep(&string, "_:"), "cd");
+  ASSERT_STREQ(__llvm_libc::strsep(&string, "_:"), "ef");
+  ASSERT_STREQ(__llvm_libc::strsep(&string, "_:"), nullptr);
+}