diff --git a/php/ext/google/protobuf/php-upb.c b/php/ext/google/protobuf/php-upb.c
index 4e75233c2b..99db650a26 100644
--- a/php/ext/google/protobuf/php-upb.c
+++ b/php/ext/google/protobuf/php-upb.c
@@ -8186,6 +8186,15 @@ static void _upb_Decoder_CheckUnlinked(upb_Decoder* d, const upb_MiniTable* mt,
   *op = kUpb_DecodeOp_UnknownField;
 }
 
+UPB_FORCEINLINE
+static void _upb_Decoder_MaybeVerifyUtf8(upb_Decoder* d,
+                                         const upb_MiniTableField* field,
+                                         int* op) {
+  if ((field->UPB_ONLYBITS(mode) & kUpb_LabelFlags_IsAlternate) &&
+      UPB_UNLIKELY(d->options & kUpb_DecodeOption_AlwaysValidateUtf8))
+    *op = kUpb_DecodeOp_String;
+}
+
 static int _upb_Decoder_GetDelimitedOp(upb_Decoder* d, const upb_MiniTable* mt,
                                        const upb_MiniTableField* field) {
   enum { kRepeatedBase = 19 };
@@ -8242,6 +8251,8 @@ static int _upb_Decoder_GetDelimitedOp(upb_Decoder* d, const upb_MiniTable* mt,
 
   if (op == kUpb_DecodeOp_SubMessage) {
     _upb_Decoder_CheckUnlinked(d, mt, field, &op);
+  } else if (op == kUpb_DecodeOp_Bytes) {
+    _upb_Decoder_MaybeVerifyUtf8(d, field, &op);
   }
 
   return op;
diff --git a/php/ext/google/protobuf/php-upb.h b/php/ext/google/protobuf/php-upb.h
index ae22247b56..872581a1bf 100644
--- a/php/ext/google/protobuf/php-upb.h
+++ b/php/ext/google/protobuf/php-upb.h
@@ -3985,6 +3985,16 @@ enum {
    *    be created by the parser or the message-copying logic in message/copy.h.
    */
   kUpb_DecodeOption_ExperimentalAllowUnlinked = 4,
+
+  /* EXPERIMENTAL:
+   *
+   * If set, decoding will enforce UTF-8 validation for string fields, even for
+   * proto2 or fields with `features.utf8_validation = NONE`. Normally, only
+   * proto3 string fields will be validated for UTF-8. Decoding will return
+   * kUpb_DecodeStatus_BadUtf8 for non-UTF-8 strings, which is the same behavior
+   * as non-UTF-8 proto3 string fields.
+   */
+  kUpb_DecodeOption_AlwaysValidateUtf8 = 8,
 };
 
 UPB_INLINE uint32_t upb_DecodeOptions_MaxDepth(uint16_t depth) {
diff --git a/ruby/ext/google/protobuf_c/ruby-upb.c b/ruby/ext/google/protobuf_c/ruby-upb.c
index 237232d282..6c848d83fe 100644
--- a/ruby/ext/google/protobuf_c/ruby-upb.c
+++ b/ruby/ext/google/protobuf_c/ruby-upb.c
@@ -7702,6 +7702,15 @@ static void _upb_Decoder_CheckUnlinked(upb_Decoder* d, const upb_MiniTable* mt,
   *op = kUpb_DecodeOp_UnknownField;
 }
 
+UPB_FORCEINLINE
+static void _upb_Decoder_MaybeVerifyUtf8(upb_Decoder* d,
+                                         const upb_MiniTableField* field,
+                                         int* op) {
+  if ((field->UPB_ONLYBITS(mode) & kUpb_LabelFlags_IsAlternate) &&
+      UPB_UNLIKELY(d->options & kUpb_DecodeOption_AlwaysValidateUtf8))
+    *op = kUpb_DecodeOp_String;
+}
+
 static int _upb_Decoder_GetDelimitedOp(upb_Decoder* d, const upb_MiniTable* mt,
                                        const upb_MiniTableField* field) {
   enum { kRepeatedBase = 19 };
@@ -7758,6 +7767,8 @@ static int _upb_Decoder_GetDelimitedOp(upb_Decoder* d, const upb_MiniTable* mt,
 
   if (op == kUpb_DecodeOp_SubMessage) {
     _upb_Decoder_CheckUnlinked(d, mt, field, &op);
+  } else if (op == kUpb_DecodeOp_Bytes) {
+    _upb_Decoder_MaybeVerifyUtf8(d, field, &op);
   }
 
   return op;
diff --git a/ruby/ext/google/protobuf_c/ruby-upb.h b/ruby/ext/google/protobuf_c/ruby-upb.h
index 433d25c131..397804a339 100755
--- a/ruby/ext/google/protobuf_c/ruby-upb.h
+++ b/ruby/ext/google/protobuf_c/ruby-upb.h
@@ -3987,6 +3987,16 @@ enum {
    *    be created by the parser or the message-copying logic in message/copy.h.
    */
   kUpb_DecodeOption_ExperimentalAllowUnlinked = 4,
+
+  /* EXPERIMENTAL:
+   *
+   * If set, decoding will enforce UTF-8 validation for string fields, even for
+   * proto2 or fields with `features.utf8_validation = NONE`. Normally, only
+   * proto3 string fields will be validated for UTF-8. Decoding will return
+   * kUpb_DecodeStatus_BadUtf8 for non-UTF-8 strings, which is the same behavior
+   * as non-UTF-8 proto3 string fields.
+   */
+  kUpb_DecodeOption_AlwaysValidateUtf8 = 8,
 };
 
 UPB_INLINE uint32_t upb_DecodeOptions_MaxDepth(uint16_t depth) {