Index: compiler-rt/lib/dfsan/dfsan_custom.cpp
===================================================================
--- compiler-rt/lib/dfsan/dfsan_custom.cpp
+++ compiler-rt/lib/dfsan/dfsan_custom.cpp
@@ -204,6 +204,55 @@
   return const_cast<char *>(ret);
 }
 
+SANITIZER_INTERFACE_ATTRIBUTE char *__dfsw_strsep(char **s, const char *delim,
+                                                  dfsan_label s_label,
+                                                  dfsan_label delim_label,
+                                                  dfsan_label *ret_label) {
+  char *base = *s;
+  char *res = strsep(s, delim);
+  if (res != *s) {
+    char *token_start = res;
+    int token_length = strlen(res);
+    // the delimiter byte has been set to NULL
+    dfsan_set_label(0, token_start + token_length, 1);
+  }
+
+  if (flags().strict_data_dependencies) {
+    *ret_label = res ? dfsan_read_label(base, sizeof(base)) : 0;
+  } else {
+    *ret_label =
+        dfsan_union(dfsan_read_label(base, sizeof(base)),
+                    dfsan_union(dfsan_read_label(delim, strlen(delim) + 1),
+                                dfsan_union(s_label, delim_label)));
+  }
+
+  return res;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE char *__dfso_strsep(
+    char **s, const char *delim, dfsan_label s_label, dfsan_label delim_label,
+    dfsan_label *ret_label, dfsan_origin s_origin, dfsan_origin delim_origin,
+    dfsan_origin *ret_origin) {
+  char *base = *s;
+  char *res = __dfsw_strsep(s, delim, s_label, delim_label, ret_label);
+  if (flags().strict_data_dependencies) {
+    if (res)
+      *ret_origin = dfsan_read_origin_of_first_taint(base, strlen(base));
+  } else {
+    if (*ret_label) {
+      dfsan_origin o = dfsan_read_origin_of_first_taint(base, strlen(base));
+      if (o) {
+        *ret_origin = o;
+      } else {
+        o = dfsan_read_origin_of_first_taint(delim, strlen(delim) + 1);
+        *ret_origin = o ? o : (s_label ? s_origin : delim_origin);
+      }
+    }
+  }
+
+  return res;
+}
+
 static int dfsan_memcmp_bcmp(const void *s1, const void *s2, size_t n,
                              size_t *bytes_read) {
   const char *cs1 = (const char *) s1, *cs2 = (const char *) s2;
Index: compiler-rt/lib/dfsan/done_abilist.txt
===================================================================
--- compiler-rt/lib/dfsan/done_abilist.txt
+++ compiler-rt/lib/dfsan/done_abilist.txt
@@ -283,6 +283,7 @@
 fun:strpbrk=custom
 fun:strrchr=custom
 fun:strstr=custom
+fun:strsep=custom
 
 # Functions which take action based on global state, such as running a callback
 # set by a separate function.
Index: compiler-rt/test/dfsan/custom.cpp
===================================================================
--- compiler-rt/test/dfsan/custom.cpp
+++ compiler-rt/test/dfsan/custom.cpp
@@ -1627,6 +1627,50 @@
 #endif
 }
 
+void test_strsep() {
+  char *s = strdup("Hello world/");
+  char *delim = strdup(" /");
+
+  char *p_s = s;
+  char *base = s;
+  char *p_delim = delim;
+
+  // taint delim bytes
+  dfsan_set_label(i_label, p_delim, strlen(p_delim));
+  // taint delim pointer
+  dfsan_set_label(j_label, &p_delim, sizeof(&p_delim));
+  // taint the string data bytes
+  dfsan_set_label(k_label, s, 5);
+  // taint the string pointer
+  dfsan_set_label(m_label, &p_s, sizeof(&p_s));
+
+  char *rv = strsep(&p_s, p_delim);
+  assert(rv == &base[0]);
+#ifdef STRICT_DATA_DEPENDENCIES
+  ASSERT_LABEL(rv, k_label);
+  ASSERT_READ_LABEL(rv, strlen(rv), k_label);
+#else
+  ASSERT_LABEL(rv, dfsan_union(dfsan_union(i_label, j_label), k_label));
+  ASSERT_INIT_ORIGIN_EQ_ORIGIN(&rv, *s);
+#endif
+
+  // taint the remaining string's pointer
+  char **pp_s = &p_s;
+  char **pp_s_base = pp_s;
+  dfsan_set_label(n_label, &pp_s, sizeof(&pp_s));
+
+  rv = strsep(pp_s, p_delim);
+
+  assert(rv == &base[6]);
+#ifdef STRICT_DATA_DEPENDENCIES
+  ASSERT_ZERO_LABEL(rv);
+  ASSERT_ZERO_ORIGIN(rv);
+#else
+  ASSERT_LABEL(rv, dfsan_union(i_label, dfsan_union(j_label, n_label)));
+  ASSERT_INIT_ORIGIN_EQ_ORIGIN(&rv, *p_delim);
+#endif
+}
+
 void test_memchr() {
   char str1[] = "str1";
   dfsan_set_label(i_label, &str1[3], 1);
@@ -2041,6 +2085,7 @@
   test_strncmp();
   test_strncpy();
   test_strpbrk();
+  test_strsep();
   test_strrchr();
   test_strstr();
   test_strtod();