diff --git a/internal.h b/internal.h
index 4c26bd2c13..9c11f4a308 100644
--- a/internal.h
+++ b/internal.h
@@ -1342,6 +1342,7 @@ VALUE rb_int_div(VALUE x, VALUE y);
 VALUE rb_int_abs(VALUE num);
 VALUE rb_float_abs(VALUE flt);
 VALUE rb_float_equal(VALUE x, VALUE y);
+VALUE rb_float_eql(VALUE x, VALUE y);
 
 #if USE_FLONUM
 #define RUBY_BIT_ROTL(v, n) (((v) << (n)) | ((v) >> ((sizeof(v) * 8) - n)))
@@ -1619,6 +1620,7 @@ size_t rb_str_memsize(VALUE);
 VALUE rb_sym_proc_call(ID mid, int argc, const VALUE *argv, VALUE passed_proc);
 VALUE rb_sym_to_proc(VALUE sym);
 char *rb_str_to_cstr(VALUE str);
+VALUE rb_str_eql(VALUE str1, VALUE str2);
 
 /* symbol.c */
 #ifdef RUBY_ENCODING_H
diff --git a/numeric.c b/numeric.c
index 69bb573cc7..8205829f8d 100644
--- a/numeric.c
+++ b/numeric.c
@@ -1643,8 +1643,8 @@ flo_le(VALUE x, VALUE y)
  *  so an implementation-dependent value is returned.
  */
 
-static VALUE
-flo_eql(VALUE x, VALUE y)
+VALUE
+rb_float_eql(VALUE x, VALUE y)
 {
     if (RB_TYPE_P(y, T_FLOAT)) {
 	double a = RFLOAT_VALUE(x);
@@ -1658,6 +1658,8 @@ flo_eql(VALUE x, VALUE y)
     return Qfalse;
 }
 
+#define flo_eql rb_float_eql
+
 /*
  * call-seq:
  *    float.to_f  ->  self
diff --git a/string.c b/string.c
index 8de556718e..54a89f3565 100644
--- a/string.c
+++ b/string.c
@@ -3183,7 +3183,7 @@ rb_str_equal(VALUE str1, VALUE str2)
  * Two strings are equal if they have the same length and content.
  */
 
-static VALUE
+VALUE
 rb_str_eql(VALUE str1, VALUE str2)
 {
     if (str1 == str2) return Qtrue;
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index a23983a5e0..b9bfccac95 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -1295,6 +1295,9 @@ check_cfunc(const rb_callable_method_entry_t *me, VALUE (*func)())
     }
 }
 
+#define BUILTIN_CLASS_P(x, k) (!SPECIAL_CONST_P(x) && RBASIC_CLASS(x) == k)
+#define EQ_UNREDEFINED_P(t) BASIC_OP_UNREDEFINED_P(BOP_EQ, t##_REDEFINED_OP_FLAG)
+
 static
 #ifndef NO_BIG_INLINE
 inline
@@ -1302,8 +1305,6 @@ inline
 VALUE
 opt_eq_func(VALUE recv, VALUE obj, CALL_INFO ci, CALL_CACHE cc)
 {
-#define BUILTIN_CLASS_P(x, k) (!SPECIAL_CONST_P(x) && RBASIC_CLASS(x) == k)
-#define EQ_UNREDEFINED_P(t) BASIC_OP_UNREDEFINED_P(BOP_EQ, t##_REDEFINED_OP_FLAG)
     if (FIXNUM_2_P(recv, obj)) {
 	if (EQ_UNREDEFINED_P(INTEGER)) {
 	    return (recv == obj) ? Qtrue : Qfalse;
@@ -1324,8 +1325,47 @@ opt_eq_func(VALUE recv, VALUE obj, CALL_INFO ci, CALL_CACHE cc)
 	    return rb_str_equal(recv, obj);
 	}
     }
-#undef EQ_UNREDEFINED_P
-#undef BUILTIN_CLASS_P
+
+    {
+	vm_search_method(ci, cc, recv);
+
+	if (check_cfunc(cc->me, rb_obj_equal)) {
+	    return recv == obj ? Qtrue : Qfalse;
+	}
+    }
+
+    return Qundef;
+}
+
+static
+#ifndef NO_BIG_INLINE
+inline
+#endif
+VALUE
+opt_eql_func(VALUE recv, VALUE obj, CALL_INFO ci, CALL_CACHE cc)
+{
+#define BUILTIN_CLASS_P(x, k) (!SPECIAL_CONST_P(x) && RBASIC_CLASS(x) == k)
+#define EQ_UNREDEFINED_P(t) BASIC_OP_UNREDEFINED_P(BOP_EQ, t##_REDEFINED_OP_FLAG)
+    if (FIXNUM_2_P(recv, obj)) {
+	if (EQ_UNREDEFINED_P(INTEGER)) {
+	    return (recv == obj) ? Qtrue : Qfalse;
+	}
+    }
+    else if (FLONUM_2_P(recv, obj)) {
+	if (EQ_UNREDEFINED_P(FLOAT)) {
+	    return (recv == obj) ? Qtrue : Qfalse;
+	}
+    }
+    else if (BUILTIN_CLASS_P(recv, rb_cFloat)) {
+	if (EQ_UNREDEFINED_P(FLOAT)) {
+	    return rb_float_eql(recv, obj);
+	}
+    }
+    else if (BUILTIN_CLASS_P(recv, rb_cString)) {
+	if (EQ_UNREDEFINED_P(STRING)) {
+	    return rb_str_eql(recv, obj);
+	}
+    }
 
     {
 	vm_search_method(ci, cc, recv);
@@ -1361,7 +1401,7 @@ rb_eql_opt(VALUE obj1, VALUE obj2)
     cc.method_state = 0;
     cc.class_serial = 0;
     cc.me = NULL;
-    return opt_eq_func(obj1, obj2, &ci, &cc);
+    return opt_eql_func(obj1, obj2, &ci, &cc);
 }
 
 static VALUE vm_call0(rb_thread_t*, VALUE, ID, int, const VALUE*, const rb_callable_method_entry_t *);