diff --git a/builtin-functions/_functions.txt b/builtin-functions/_functions.txt
index af35a1d43f..2c71ffee3e 100644
--- a/builtin-functions/_functions.txt
+++ b/builtin-functions/_functions.txt
@@ -663,6 +663,7 @@ function substr_compare ($main_str ::: string, $str ::: string, $offset ::: int,
 
 function str_starts_with ($haystack ::: string, $needle ::: string) ::: bool;
 function str_ends_with ($haystack ::: string, $needle ::: string) ::: bool;
+function str_contains ($haystack ::: string, $needle ::: string) ::: bool;
 
 function trim ($s ::: string, $what ::: string = " \n\r\t\v\0") ::: string;
 function ltrim ($s ::: string, $what ::: string = " \n\r\t\v\0") ::: string;
diff --git a/runtime/string.inl b/runtime/string.inl
index 03ac0cf420..f3812a20e8 100644
--- a/runtime/string.inl
+++ b/runtime/string.inl
@@ -344,6 +344,20 @@ bool string::ends_with(const string &other) const noexcept {
   return other.size() > size() ? false : !memcmp(c_str() + (size() - other.size()), other.c_str(), other.size());
 }
 
+bool string::contains(const string &other) const noexcept {
+  if (other.size() > size()) {
+    return false;
+  }
+
+  for (size_type i = 0; i < (size() - other.size() + 1); i++) {
+    if (memcmp(c_str() + i, other.c_str(), other.size()) == 0) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 const char &string::operator[](size_type pos) const {
   return p[pos];
 }
diff --git a/runtime/string_decl.inl b/runtime/string_decl.inl
index 6a51c582be..334b88069c 100644
--- a/runtime/string_decl.inl
+++ b/runtime/string_decl.inl
@@ -96,6 +96,7 @@ public:
   inline bool empty() const;
   inline bool starts_with(const string &other) const noexcept;
   inline bool ends_with(const string &other) const noexcept;
+  inline bool contains(const string &other) const noexcept;
 
   inline const char &operator[](size_type pos) const;
   inline char &operator[](size_type pos);
diff --git a/runtime/string_functions.cpp b/runtime/string_functions.cpp
index 7c483b077d..7ed984dcad 100644
--- a/runtime/string_functions.cpp
+++ b/runtime/string_functions.cpp
@@ -2327,6 +2327,10 @@ bool f$str_ends_with(const string &haystack, const string &needle) {
   return haystack.ends_with(needle);
 }
 
+bool f$str_contains(const string &haystack, const string &needle) {
+  return haystack.contains(needle);
+}
+
 string f$trim(const string &s, const string &what) {
   const char *mask = get_mask(what);
 
diff --git a/runtime/string_functions.h b/runtime/string_functions.h
index 28f339c4d1..4f1e3b9f2f 100644
--- a/runtime/string_functions.h
+++ b/runtime/string_functions.h
@@ -236,6 +236,8 @@ bool f$str_starts_with(const string &haystack, const string &needle);
 
 bool f$str_ends_with(const string &haystack, const string &needle);
 
+bool f$str_contains(const string &haystack, const string &needle);
+
 string f$trim(const string &s, const string &what = WHAT);
 
 string f$ucfirst(const string &str);
diff --git a/tests/cpp/runtime/string-test.cpp b/tests/cpp/runtime/string-test.cpp
index 7423fc95ab..53faec110c 100644
--- a/tests/cpp/runtime/string-test.cpp
+++ b/tests/cpp/runtime/string-test.cpp
@@ -56,6 +56,25 @@ TEST(string_test, test_ends_with) {
   ASSERT_FALSE(str.starts_with(string{"hello world!"}));
 }
 
+TEST(string_test, test_contains) {
+  string empty_str{""};
+  ASSERT_TRUE(empty_str.contains(string{""}));
+  ASSERT_FALSE(empty_str.contains(string{"a"}));
+
+  string str{"hello world"};
+  ASSERT_TRUE(str.contains(string{"hello"}));
+  ASSERT_TRUE(str.contains(string{"world"}));
+  ASSERT_TRUE(str.contains(string{"orld"}));
+  ASSERT_TRUE(str.contains(string{"o w"}));
+  ASSERT_TRUE(str.contains(string{"d"}));
+  ASSERT_TRUE(str.contains(string{""}));
+
+  ASSERT_FALSE(str.contains(string{"hEllo"}));
+  ASSERT_FALSE(str.contains(string{"o W"}));
+
+  ASSERT_FALSE(str.contains(string{"hello world!"}));
+}
+
 TEST(string_test, test_make_const_string_on_memory) {
   char mem[1024];
 
diff --git a/tests/python/tests/composer/php/test_autoload_files/lib/polyfills/file2.php b/tests/python/tests/composer/php/test_autoload_files/lib/polyfills/file2.php
index 2c8d5e2cb8..c82eed9ac7 100644
--- a/tests/python/tests/composer/php/test_autoload_files/lib/polyfills/file2.php
+++ b/tests/python/tests/composer/php/test_autoload_files/lib/polyfills/file2.php
@@ -3,8 +3,10 @@
 global $global_map;
 $global_map[__FILE__] = true;
 
+#ifndef KPHP
 if (!function_exists('str_contains')) {
   function str_contains(string $haystack, string $needle): bool {
     return '' === $needle || false !== strpos($haystack, $needle);
   }
 }
+#endif