diff --git a/go.mod b/go.mod
index 26dbf5d706..c65c56d005 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,4 @@ module github.com/golang/protobuf
 
 go 1.9
 
-require google.golang.org/protobuf v0.0.0-20190620020611-d888139e7b59
+require google.golang.org/protobuf v0.0.0-20190717230113-f647c82cc3c7
diff --git a/go.sum b/go.sum
index 46ffa01ea3..ae4387fee5 100644
--- a/go.sum
+++ b/go.sum
@@ -5,6 +5,7 @@ github.com/golang/protobuf v1.2.1-0.20190516215712-ae2eaafab405/go.mod h1:UmP8hh
 github.com/golang/protobuf v1.2.1-0.20190523175523-a1331f0b4ab4/go.mod h1:G+fNMoyvKWZDB7PCDHF+dXbH9OeE3+JoozCd9V7i66U=
 github.com/golang/protobuf v1.2.1-0.20190605195750-76c9e09470ba/go.mod h1:S1YIJXvYHGRCG2UmZsOcElkAYfvZLg2sDRr9+Xu8JXU=
 github.com/golang/protobuf v1.2.1-0.20190617175902-f94016f5239f/go.mod h1:G+HpKX7pYZAVkElkAWZkr08MToW6pTp/vs+E9osFfbg=
+github.com/golang/protobuf v1.2.1-0.20190620192300-1ee46dfd80dd/go.mod h1:+CMAsi9jpYf/wAltLUKlg++CWXqxCJyD8iLDbQONsJs=
 github.com/google/go-cmp v0.3.0 h1:crn/baboCvb5fXaQ0IJ1SGTsTVrWpDsCWC8EGETZijY=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 google.golang.org/protobuf v0.0.0-20190514172829-e89e6244e0e8/go.mod h1:791zQGC15vDqjpmPRn1uGPu5oHy/Jzw/Q1n5JsgIIcY=
@@ -14,5 +15,6 @@ google.golang.org/protobuf v0.0.0-20190516215540-a95b29fbf623/go.mod h1:cWWmz5ls
 google.golang.org/protobuf v0.0.0-20190522194032-21ade498bd69/go.mod h1:cJytyYi/6qdwy/+gD49hmgHcwD7zhWxE/1KPEslaZ3M=
 google.golang.org/protobuf v0.0.0-20190605195314-89d49632e5cf/go.mod h1:Btug4TBaP5wNYcb2zGKDTS7WMcaPPLuqEAKfEAZWYbo=
 google.golang.org/protobuf v0.0.0-20190617175724-bd7b7a9e0c26/go.mod h1:+FOB8T5/Yw4ywwdyeun9/KlDeuwFYBkNQ+kVuwj9C94=
-google.golang.org/protobuf v0.0.0-20190620020611-d888139e7b59 h1:8413FO+8BbzBumkamWfo1VRHJyPBKBUeerQodlLbb0g=
 google.golang.org/protobuf v0.0.0-20190620020611-d888139e7b59/go.mod h1:of3pt14Y+dOxz2tBOHXEoapPpKFC15/0zWhPAddkfsU=
+google.golang.org/protobuf v0.0.0-20190717230113-f647c82cc3c7 h1:U6U+Hb+UKNGJB0eMAjUGk0wTmy73kduTIvdsEgA4Gf8=
+google.golang.org/protobuf v0.0.0-20190717230113-f647c82cc3c7/go.mod h1:yGm7aNHn9Bp1NIvj6+CVUkcJshu+Usshfd3A+YxEuI8=
diff --git a/internal/proto/properties.go b/internal/proto/properties.go
index a3d024b6c3..d129248e01 100644
--- a/internal/proto/properties.go
+++ b/internal/proto/properties.go
@@ -11,6 +11,7 @@ import (
 	"strings"
 	"sync"
 
+	protoV2 "google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/runtime/protoimpl"
 )
 
@@ -251,10 +252,10 @@ func newProperties(t reflect.Type) *StructProperties {
 			p.OrigName = tagOneof
 		}
 
-		// Rename unrelated struct fields with the "XXX_" prefix since so much
-		// user code simply checks for this to exclude special fields.
-		if tagField == "" && tagOneof == "" && !strings.HasPrefix(p.Name, "XXX_") {
-			p.Name = "XXX_invalid_" + p.Name
+		// Rename unexported struct fields with the "XXX_" prefix since so much
+		// user code simply checks for this to exclude unrelated fields.
+		if f.PkgPath != "" {
+			p.Name = "XXX_" + p.Name
 		}
 
 		prop.Prop = append(prop.Prop, p)
@@ -268,6 +269,11 @@ func newProperties(t reflect.Type) *StructProperties {
 	if fn, ok := reflect.PtrTo(t).MethodByName("XXX_OneofWrappers"); ok {
 		oneofWrappers = fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[0].Interface().([]interface{})
 	}
+	if m, ok := reflect.Zero(reflect.PtrTo(t)).Interface().(protoV2.Message); ok {
+		if m, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *protoimpl.MessageInfo }); ok {
+			oneofWrappers = m.ProtoMessageInfo().OneofWrappers
+		}
+	}
 	if len(oneofWrappers) > 0 {
 		prop.OneofTypes = make(map[string]*OneofProperties)
 		for _, wrapper := range oneofWrappers {
diff --git a/jsonpb/jsonpb.go b/jsonpb/jsonpb.go
index 6bcb71946e..0d817d5e17 100644
--- a/jsonpb/jsonpb.go
+++ b/jsonpb/jsonpb.go
@@ -23,6 +23,8 @@ import (
 	"time"
 
 	"github.com/golang/protobuf/proto"
+	protoV2 "google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protoreflect"
 
 	stpb "github.com/golang/protobuf/ptypes/struct"
 )
@@ -131,8 +133,31 @@ func (s int32Slice) Len() int           { return len(s) }
 func (s int32Slice) Less(i, j int) bool { return s[i] < s[j] }
 func (s int32Slice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 
-type wkt interface {
-	XXX_WellKnownType() string
+func wellKnownType(v interface{}) string {
+	var s protoreflect.FullName
+	switch v := v.(type) {
+	case interface{ XXX_WellKnownType() string }:
+		return v.XXX_WellKnownType()
+	case protoreflect.Enum:
+		s = v.Descriptor().FullName()
+	case protoreflect.ProtoMessage:
+		s = v.ProtoReflect().Descriptor().FullName()
+	}
+	if s.Parent() == "google.protobuf" {
+		switch s.Name() {
+		case "Empty",
+			"Any",
+			"BoolValue",
+			"FloatValue", "DoubleValue",
+			"Int32Value", "Int64Value",
+			"UInt32Value", "UInt64Value",
+			"BytesValue", "StringValue",
+			"Duration", "Timestamp",
+			"NullValue", "Struct", "Value", "ListValue":
+			return string(s.Name())
+		}
+	}
+	return ""
 }
 
 // marshalObject writes a struct to the Writer.
@@ -165,71 +190,69 @@ func (m *Marshaler) marshalObject(out *errWriter, v proto.Message, indent, typeU
 	s := reflect.ValueOf(v).Elem()
 
 	// Handle well-known types.
-	if wkt, ok := v.(wkt); ok {
-		switch wkt.XXX_WellKnownType() {
-		case "DoubleValue", "FloatValue", "Int64Value", "UInt64Value",
-			"Int32Value", "UInt32Value", "BoolValue", "StringValue", "BytesValue":
-			// "Wrappers use the same representation in JSON
-			//  as the wrapped primitive type, ..."
-			sprop := proto.GetProperties(s.Type())
-			return m.marshalValue(out, sprop.Prop[0], s.Field(0), indent)
-		case "Any":
-			// Any is a bit more involved.
-			return m.marshalAny(out, v, indent)
-		case "Duration":
-			// "Generated output always contains 0, 3, 6, or 9 fractional digits,
-			//  depending on required precision."
-			s, ns := s.Field(0).Int(), s.Field(1).Int()
-			if ns <= -secondInNanos || ns >= secondInNanos {
-				return fmt.Errorf("ns out of range (%v, %v)", -secondInNanos, secondInNanos)
-			}
-			if (s > 0 && ns < 0) || (s < 0 && ns > 0) {
-				return errors.New("signs of seconds and nanos do not match")
-			}
-			if s < 0 {
-				ns = -ns
-			}
-			x := fmt.Sprintf("%d.%09d", s, ns)
-			x = strings.TrimSuffix(x, "000")
-			x = strings.TrimSuffix(x, "000")
-			x = strings.TrimSuffix(x, ".000")
-			out.write(`"`)
-			out.write(x)
-			out.write(`s"`)
-			return out.err
-		case "Struct", "ListValue":
-			// Let marshalValue handle the `Struct.fields` map or the `ListValue.values` slice.
-			// TODO: pass the correct Properties if needed.
-			return m.marshalValue(out, &proto.Properties{}, s.Field(0), indent)
-		case "Timestamp":
-			// "RFC 3339, where generated output will always be Z-normalized
-			//  and uses 0, 3, 6 or 9 fractional digits."
-			s, ns := s.Field(0).Int(), s.Field(1).Int()
-			if ns < 0 || ns >= secondInNanos {
-				return fmt.Errorf("ns out of range [0, %v)", secondInNanos)
-			}
-			t := time.Unix(s, ns).UTC()
-			// time.RFC3339Nano isn't exactly right (we need to get 3/6/9 fractional digits).
-			x := t.Format("2006-01-02T15:04:05.000000000")
-			x = strings.TrimSuffix(x, "000")
-			x = strings.TrimSuffix(x, "000")
-			x = strings.TrimSuffix(x, ".000")
-			out.write(`"`)
-			out.write(x)
-			out.write(`Z"`)
-			return out.err
-		case "Value":
-			// Value has a single oneof.
-			kind := s.Field(0)
-			if kind.IsNil() {
-				// "absence of any variant indicates an error"
-				return errors.New("nil Value")
-			}
-			// oneof -> *T -> T -> T.F
-			x := kind.Elem().Elem().Field(0)
-			// TODO: pass the correct Properties if needed.
-			return m.marshalValue(out, &proto.Properties{}, x, indent)
+	switch wellKnownType(v) {
+	case "DoubleValue", "FloatValue", "Int64Value", "UInt64Value",
+		"Int32Value", "UInt32Value", "BoolValue", "StringValue", "BytesValue":
+		// "Wrappers use the same representation in JSON
+		//  as the wrapped primitive type, ..."
+		sprop := proto.GetProperties(s.Type())
+		return m.marshalValue(out, sprop.Prop[1], s.Field(1), indent)
+	case "Any":
+		// Any is a bit more involved.
+		return m.marshalAny(out, v, indent)
+	case "Duration":
+		// "Generated output always contains 0, 3, 6, or 9 fractional digits,
+		//  depending on required precision."
+		s, ns := s.Field(1).Int(), s.Field(2).Int()
+		if ns <= -secondInNanos || ns >= secondInNanos {
+			return fmt.Errorf("ns out of range (%v, %v)", -secondInNanos, secondInNanos)
+		}
+		if (s > 0 && ns < 0) || (s < 0 && ns > 0) {
+			return errors.New("signs of seconds and nanos do not match")
+		}
+		if s < 0 {
+			ns = -ns
+		}
+		x := fmt.Sprintf("%d.%09d", s, ns)
+		x = strings.TrimSuffix(x, "000")
+		x = strings.TrimSuffix(x, "000")
+		x = strings.TrimSuffix(x, ".000")
+		out.write(`"`)
+		out.write(x)
+		out.write(`s"`)
+		return out.err
+	case "Struct", "ListValue":
+		// Let marshalValue handle the `Struct.fields` map or the `ListValue.values` slice.
+		// TODO: pass the correct Properties if needed.
+		return m.marshalValue(out, &proto.Properties{}, s.Field(1), indent)
+	case "Timestamp":
+		// "RFC 3339, where generated output will always be Z-normalized
+		//  and uses 0, 3, 6 or 9 fractional digits."
+		s, ns := s.Field(1).Int(), s.Field(2).Int()
+		if ns < 0 || ns >= secondInNanos {
+			return fmt.Errorf("ns out of range [0, %v)", secondInNanos)
+		}
+		t := time.Unix(s, ns).UTC()
+		// time.RFC3339Nano isn't exactly right (we need to get 3/6/9 fractional digits).
+		x := t.Format("2006-01-02T15:04:05.000000000")
+		x = strings.TrimSuffix(x, "000")
+		x = strings.TrimSuffix(x, "000")
+		x = strings.TrimSuffix(x, ".000")
+		out.write(`"`)
+		out.write(x)
+		out.write(`Z"`)
+		return out.err
+	case "Value":
+		// Value has a single oneof.
+		kind := s.Field(1)
+		if kind.IsNil() {
+			// "absence of any variant indicates an error"
+			return errors.New("nil Value")
 		}
+		// oneof -> *T -> T -> T.F
+		x := kind.Elem().Elem().Field(0)
+		// TODO: pass the correct Properties if needed.
+		return m.marshalValue(out, &proto.Properties{}, x, indent)
 	}
 
 	out.write("{")
@@ -247,11 +270,11 @@ func (m *Marshaler) marshalObject(out *errWriter, v proto.Message, indent, typeU
 	}
 
 	for i := 0; i < s.NumField(); i++ {
-		value := s.Field(i)
-		valueField := s.Type().Field(i)
-		if strings.HasPrefix(valueField.Name, "XXX_") {
+		if f := s.Type().Field(i); strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
+		value := s.Field(i)
+		valueField := s.Type().Field(i)
 
 		// IsNil will panic on most value kinds.
 		switch value.Kind() {
@@ -332,7 +355,11 @@ func (m *Marshaler) marshalObject(out *errWriter, v proto.Message, indent, typeU
 			value := reflect.ValueOf(ext)
 			var prop proto.Properties
 			prop.Parse(desc.Tag)
-			prop.JSONName = fmt.Sprintf("[%s]", desc.Name)
+			name := desc.Name
+			if strings.HasSuffix(name, ".message_set_extension") && isMessageSet(s.Type()) {
+				name = strings.TrimSuffix(name, ".message_set_extension")
+			}
+			prop.JSONName = fmt.Sprintf("[%s]", name)
 			if !firstField {
 				m.writeSep(out)
 			}
@@ -366,8 +393,8 @@ func (m *Marshaler) marshalAny(out *errWriter, any proto.Message, indent string)
 	//  Otherwise, the value will be converted into a JSON object,
 	//  and the "@type" field will be inserted to indicate the actual data type."
 	v := reflect.ValueOf(any).Elem()
-	turl := v.Field(0).String()
-	val := v.Field(1).Bytes()
+	turl := v.Field(1).String()
+	val := v.Field(2).Bytes()
 
 	var msg proto.Message
 	var err error
@@ -384,7 +411,7 @@ func (m *Marshaler) marshalAny(out *errWriter, any proto.Message, indent string)
 		return err
 	}
 
-	if _, ok := msg.(wkt); ok {
+	if wellKnownType(msg) != "" {
 		out.write("{")
 		if m.Indent != "" {
 			out.write("\n")
@@ -489,12 +516,10 @@ func (m *Marshaler) marshalValue(out *errWriter, prop *proto.Properties, v refle
 
 	// Handle well-known types.
 	// Most are handled up in marshalObject (because 99% are messages).
-	if wkt, ok := v.Interface().(wkt); ok {
-		switch wkt.XXX_WellKnownType() {
-		case "NullValue":
-			out.write("null")
-			return out.err
-		}
+	switch wellKnownType(v.Interface()) {
+	case "NullValue":
+		out.write("null")
+		return out.err
 	}
 
 	// Handle enumerations.
@@ -695,152 +720,150 @@ func (u *Unmarshaler) unmarshalValue(target reflect.Value, inputValue json.RawMe
 	}
 
 	// Handle well-known types that are not pointers.
-	if w, ok := target.Addr().Interface().(wkt); ok {
-		switch w.XXX_WellKnownType() {
-		case "DoubleValue", "FloatValue", "Int64Value", "UInt64Value",
-			"Int32Value", "UInt32Value", "BoolValue", "StringValue", "BytesValue":
-			return u.unmarshalValue(target.Field(0), inputValue, prop)
-		case "Any":
-			// Use json.RawMessage pointer type instead of value to support pre-1.8 version.
-			// 1.8 changed RawMessage.MarshalJSON from pointer type to value type, see
-			// https://github.com/golang/go/issues/14493
-			var jsonFields map[string]*json.RawMessage
-			if err := json.Unmarshal(inputValue, &jsonFields); err != nil {
-				return err
-			}
-
-			val, ok := jsonFields["@type"]
-			if !ok || val == nil {
-				return errors.New("Any JSON doesn't have '@type'")
-			}
+	switch wellKnownType(target.Addr().Interface()) {
+	case "DoubleValue", "FloatValue", "Int64Value", "UInt64Value",
+		"Int32Value", "UInt32Value", "BoolValue", "StringValue", "BytesValue":
+		return u.unmarshalValue(target.Field(1), inputValue, prop)
+	case "Any":
+		// Use json.RawMessage pointer type instead of value to support pre-1.8 version.
+		// 1.8 changed RawMessage.MarshalJSON from pointer type to value type, see
+		// https://github.com/golang/go/issues/14493
+		var jsonFields map[string]*json.RawMessage
+		if err := json.Unmarshal(inputValue, &jsonFields); err != nil {
+			return err
+		}
 
-			var turl string
-			if err := json.Unmarshal([]byte(*val), &turl); err != nil {
-				return fmt.Errorf("can't unmarshal Any's '@type': %q", *val)
-			}
-			target.Field(0).SetString(turl)
-
-			var m proto.Message
-			var err error
-			if u.AnyResolver != nil {
-				m, err = u.AnyResolver.Resolve(turl)
-			} else {
-				m, err = defaultResolveAny(turl)
-			}
-			if err != nil {
-				return err
-			}
+		val, ok := jsonFields["@type"]
+		if !ok || val == nil {
+			return errors.New("Any JSON doesn't have '@type'")
+		}
 
-			if _, ok := m.(wkt); ok {
-				val, ok := jsonFields["value"]
-				if !ok {
-					return errors.New("Any JSON doesn't have 'value'")
-				}
+		var turl string
+		if err := json.Unmarshal([]byte(*val), &turl); err != nil {
+			return fmt.Errorf("can't unmarshal Any's '@type': %q", *val)
+		}
+		target.Field(1).SetString(turl)
 
-				if err := u.unmarshalValue(reflect.ValueOf(m).Elem(), *val, nil); err != nil {
-					return fmt.Errorf("can't unmarshal Any nested proto %T: %v", m, err)
-				}
-			} else {
-				delete(jsonFields, "@type")
-				nestedProto, err := json.Marshal(jsonFields)
-				if err != nil {
-					return fmt.Errorf("can't generate JSON for Any's nested proto to be unmarshaled: %v", err)
-				}
+		var m proto.Message
+		var err error
+		if u.AnyResolver != nil {
+			m, err = u.AnyResolver.Resolve(turl)
+		} else {
+			m, err = defaultResolveAny(turl)
+		}
+		if err != nil {
+			return err
+		}
 
-				if err = u.unmarshalValue(reflect.ValueOf(m).Elem(), nestedProto, nil); err != nil {
-					return fmt.Errorf("can't unmarshal Any nested proto %T: %v", m, err)
-				}
+		if wellKnownType(m) != "" {
+			val, ok := jsonFields["value"]
+			if !ok {
+				return errors.New("Any JSON doesn't have 'value'")
 			}
 
-			b, err := proto.Marshal(m)
-			if err != nil {
-				return fmt.Errorf("can't marshal proto %T into Any.Value: %v", m, err)
+			if err := u.unmarshalValue(reflect.ValueOf(m).Elem(), *val, nil); err != nil {
+				return fmt.Errorf("can't unmarshal Any nested proto %T: %v", m, err)
 			}
-			target.Field(1).SetBytes(b)
-
-			return nil
-		case "Duration":
-			unq, err := unquote(string(inputValue))
+		} else {
+			delete(jsonFields, "@type")
+			nestedProto, err := json.Marshal(jsonFields)
 			if err != nil {
-				return err
+				return fmt.Errorf("can't generate JSON for Any's nested proto to be unmarshaled: %v", err)
 			}
 
-			d, err := time.ParseDuration(unq)
-			if err != nil {
-				return fmt.Errorf("bad Duration: %v", err)
+			if err = u.unmarshalValue(reflect.ValueOf(m).Elem(), nestedProto, nil); err != nil {
+				return fmt.Errorf("can't unmarshal Any nested proto %T: %v", m, err)
 			}
+		}
 
-			ns := d.Nanoseconds()
-			s := ns / 1e9
-			ns %= 1e9
-			target.Field(0).SetInt(s)
-			target.Field(1).SetInt(ns)
-			return nil
-		case "Timestamp":
-			unq, err := unquote(string(inputValue))
-			if err != nil {
-				return err
-			}
+		b, err := proto.Marshal(m)
+		if err != nil {
+			return fmt.Errorf("can't marshal proto %T into Any.Value: %v", m, err)
+		}
+		target.Field(2).SetBytes(b)
 
-			t, err := time.Parse(time.RFC3339Nano, unq)
-			if err != nil {
-				return fmt.Errorf("bad Timestamp: %v", err)
-			}
+		return nil
+	case "Duration":
+		unq, err := unquote(string(inputValue))
+		if err != nil {
+			return err
+		}
 
-			target.Field(0).SetInt(t.Unix())
-			target.Field(1).SetInt(int64(t.Nanosecond()))
-			return nil
-		case "Struct":
-			var m map[string]json.RawMessage
-			if err := json.Unmarshal(inputValue, &m); err != nil {
-				return fmt.Errorf("bad StructValue: %v", err)
-			}
+		d, err := time.ParseDuration(unq)
+		if err != nil {
+			return fmt.Errorf("bad Duration: %v", err)
+		}
 
-			target.Field(0).Set(reflect.ValueOf(map[string]*stpb.Value{}))
-			for k, jv := range m {
-				pv := &stpb.Value{}
-				if err := u.unmarshalValue(reflect.ValueOf(pv).Elem(), jv, prop); err != nil {
-					return fmt.Errorf("bad value in StructValue for key %q: %v", k, err)
-				}
-				target.Field(0).SetMapIndex(reflect.ValueOf(k), reflect.ValueOf(pv))
-			}
-			return nil
-		case "ListValue":
-			var s []json.RawMessage
-			if err := json.Unmarshal(inputValue, &s); err != nil {
-				return fmt.Errorf("bad ListValue: %v", err)
-			}
+		ns := d.Nanoseconds()
+		s := ns / 1e9
+		ns %= 1e9
+		target.Field(1).SetInt(s)
+		target.Field(2).SetInt(ns)
+		return nil
+	case "Timestamp":
+		unq, err := unquote(string(inputValue))
+		if err != nil {
+			return err
+		}
 
-			target.Field(0).Set(reflect.ValueOf(make([]*stpb.Value, len(s))))
-			for i, sv := range s {
-				if err := u.unmarshalValue(target.Field(0).Index(i), sv, prop); err != nil {
-					return err
-				}
+		t, err := time.Parse(time.RFC3339Nano, unq)
+		if err != nil {
+			return fmt.Errorf("bad Timestamp: %v", err)
+		}
+
+		target.Field(1).SetInt(t.Unix())
+		target.Field(2).SetInt(int64(t.Nanosecond()))
+		return nil
+	case "Struct":
+		var m map[string]json.RawMessage
+		if err := json.Unmarshal(inputValue, &m); err != nil {
+			return fmt.Errorf("bad StructValue: %v", err)
+		}
+
+		target.Field(1).Set(reflect.ValueOf(map[string]*stpb.Value{}))
+		for k, jv := range m {
+			pv := &stpb.Value{}
+			if err := u.unmarshalValue(reflect.ValueOf(pv).Elem(), jv, prop); err != nil {
+				return fmt.Errorf("bad value in StructValue for key %q: %v", k, err)
 			}
-			return nil
-		case "Value":
-			ivStr := string(inputValue)
-			if ivStr == "null" {
-				target.Field(0).Set(reflect.ValueOf(&stpb.Value_NullValue{}))
-			} else if v, err := strconv.ParseFloat(ivStr, 0); err == nil {
-				target.Field(0).Set(reflect.ValueOf(&stpb.Value_NumberValue{v}))
-			} else if v, err := unquote(ivStr); err == nil {
-				target.Field(0).Set(reflect.ValueOf(&stpb.Value_StringValue{v}))
-			} else if v, err := strconv.ParseBool(ivStr); err == nil {
-				target.Field(0).Set(reflect.ValueOf(&stpb.Value_BoolValue{v}))
-			} else if err := json.Unmarshal(inputValue, &[]json.RawMessage{}); err == nil {
-				lv := &stpb.ListValue{}
-				target.Field(0).Set(reflect.ValueOf(&stpb.Value_ListValue{lv}))
-				return u.unmarshalValue(reflect.ValueOf(lv).Elem(), inputValue, prop)
-			} else if err := json.Unmarshal(inputValue, &map[string]json.RawMessage{}); err == nil {
-				sv := &stpb.Struct{}
-				target.Field(0).Set(reflect.ValueOf(&stpb.Value_StructValue{sv}))
-				return u.unmarshalValue(reflect.ValueOf(sv).Elem(), inputValue, prop)
-			} else {
-				return fmt.Errorf("unrecognized type for Value %q", ivStr)
+			target.Field(1).SetMapIndex(reflect.ValueOf(k), reflect.ValueOf(pv))
+		}
+		return nil
+	case "ListValue":
+		var s []json.RawMessage
+		if err := json.Unmarshal(inputValue, &s); err != nil {
+			return fmt.Errorf("bad ListValue: %v", err)
+		}
+
+		target.Field(1).Set(reflect.ValueOf(make([]*stpb.Value, len(s))))
+		for i, sv := range s {
+			if err := u.unmarshalValue(target.Field(1).Index(i), sv, prop); err != nil {
+				return err
 			}
-			return nil
 		}
+		return nil
+	case "Value":
+		ivStr := string(inputValue)
+		if ivStr == "null" {
+			target.Field(1).Set(reflect.ValueOf(&stpb.Value_NullValue{}))
+		} else if v, err := strconv.ParseFloat(ivStr, 0); err == nil {
+			target.Field(1).Set(reflect.ValueOf(&stpb.Value_NumberValue{v}))
+		} else if v, err := unquote(ivStr); err == nil {
+			target.Field(1).Set(reflect.ValueOf(&stpb.Value_StringValue{v}))
+		} else if v, err := strconv.ParseBool(ivStr); err == nil {
+			target.Field(1).Set(reflect.ValueOf(&stpb.Value_BoolValue{v}))
+		} else if err := json.Unmarshal(inputValue, &[]json.RawMessage{}); err == nil {
+			lv := &stpb.ListValue{}
+			target.Field(1).Set(reflect.ValueOf(&stpb.Value_ListValue{lv}))
+			return u.unmarshalValue(reflect.ValueOf(lv).Elem(), inputValue, prop)
+		} else if err := json.Unmarshal(inputValue, &map[string]json.RawMessage{}); err == nil {
+			sv := &stpb.Struct{}
+			target.Field(1).Set(reflect.ValueOf(&stpb.Value_StructValue{sv}))
+			return u.unmarshalValue(reflect.ValueOf(sv).Elem(), inputValue, prop)
+		} else {
+			return fmt.Errorf("unrecognized type for Value %q", ivStr)
+		}
+		return nil
 	}
 
 	// Handle enums, which have an underlying type of int32,
@@ -899,7 +922,7 @@ func (u *Unmarshaler) unmarshalValue(target reflect.Value, inputValue json.RawMe
 		sprops := proto.GetProperties(targetType)
 		for i := 0; i < target.NumField(); i++ {
 			ft := target.Type().Field(i)
-			if strings.HasPrefix(ft.Name, "XXX_") {
+			if f := ft; strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 				continue
 			}
 
@@ -944,6 +967,23 @@ func (u *Unmarshaler) unmarshalValue(target reflect.Value, inputValue json.RawMe
 						return err
 					}
 				}
+				if isMessageSet(target.Type()) {
+					for _, ext := range proto.RegisteredExtensions(ep) {
+						name := fmt.Sprintf("[%s]", strings.TrimSuffix(ext.Name, ".message_set_extension"))
+						raw, ok := jsonFields[name]
+						if !ok {
+							continue
+						}
+						delete(jsonFields, name)
+						nv := reflect.New(reflect.TypeOf(ext.ExtensionType).Elem())
+						if err := u.unmarshalValue(nv.Elem(), raw, nil); err != nil {
+							return err
+						}
+						if err := proto.SetExtension(ep, ext, nv.Interface()); err != nil {
+							return err
+						}
+					}
+				}
 			}
 		}
 		if !u.AllowUnknownFields && len(jsonFields) > 0 {
@@ -1118,7 +1158,7 @@ func checkRequiredFields(pb proto.Message) error {
 	// When an Any message is being unmarshaled, the code will have invoked proto.Marshal on the
 	// embedded message to store the serialized message in Any.Value field, and that should have
 	// returned an error if a required field is not set.
-	if _, ok := pb.(wkt); ok {
+	if wellKnownType(pb) != "" {
 		return nil
 	}
 
@@ -1133,17 +1173,11 @@ func checkRequiredFields(pb proto.Message) error {
 	}
 
 	for i := 0; i < v.NumField(); i++ {
-		field := v.Field(i)
-		sfield := v.Type().Field(i)
-
-		if sfield.PkgPath != "" {
-			// blank PkgPath means the field is exported; skip if not exported
-			continue
-		}
-
-		if strings.HasPrefix(sfield.Name, "XXX_") {
+		if f := v.Type().Field(i); strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
+		field := v.Field(i)
+		sfield := v.Type().Field(i)
 
 		// Oneof field is an interface implemented by wrapper structs containing the actual oneof
 		// field, i.e. an interface containing &T{real_value}.
@@ -1240,3 +1274,14 @@ func checkRequiredFieldsInValue(v reflect.Value) error {
 	}
 	return nil
 }
+
+// isMessageSet determines whether t is a MessageSet message,
+// where t must be a named struct type.
+func isMessageSet(t reflect.Type) bool {
+	if m, ok := reflect.Zero(reflect.PtrTo(t)).Interface().(protoV2.Message); ok {
+		md := m.ProtoReflect().Descriptor()
+		xmd, ok := md.(interface{ IsMessageSet() bool })
+		return ok && xmd.IsMessageSet()
+	}
+	return false
+}
diff --git a/jsonpb/jsonpb_test.go b/jsonpb/jsonpb_test.go
index 93ed06d3a1..d58a803749 100644
--- a/jsonpb/jsonpb_test.go
+++ b/jsonpb/jsonpb_test.go
@@ -506,7 +506,7 @@ func TestMarshaling(t *testing.T) {
 		if err != nil {
 			t.Errorf("%s: marshaling error: %v", tt.desc, err)
 		} else if tt.json != json {
-			t.Errorf("%s: got [%v] want [%v]", tt.desc, json, tt.json)
+			t.Errorf("%s:\ngot:  %v\nwant: %v", tt.desc, json, tt.json)
 		}
 	}
 }
diff --git a/proto/all_test.go b/proto/all_test.go
index ad586f6484..2c8e3aadc0 100644
--- a/proto/all_test.go
+++ b/proto/all_test.go
@@ -21,6 +21,7 @@ import (
 	. "github.com/golang/protobuf/proto"
 	pb3 "github.com/golang/protobuf/proto/proto3_proto"
 	. "github.com/golang/protobuf/proto/test_proto"
+	tpb "google.golang.org/protobuf/types/known/timestamppb"
 )
 
 var globalO *Buffer
@@ -2328,6 +2329,15 @@ func TestRequired(t *testing.T) {
 	}
 }
 
+func TestUnknownV2(t *testing.T) {
+	m := new(tpb.Timestamp)
+	m.ProtoReflect().SetUnknown([]byte("\x92\x4d\x12unknown field 1234"))
+	got := CompactTextString(m)
+	if !strings.Contains(got, "unknown field 1234") {
+		t.Errorf("got %q, want contains %q", got, "unknown field 1234")
+	}
+}
+
 // Benchmarks
 
 func testMsg() *GoTest {
diff --git a/proto/clone.go b/proto/clone.go
index cd1a2e20a4..c753078df4 100644
--- a/proto/clone.go
+++ b/proto/clone.go
@@ -77,7 +77,7 @@ func mergeStruct(out, in reflect.Value) {
 	sprop := GetProperties(in.Type())
 	for i := 0; i < in.NumField(); i++ {
 		f := in.Type().Field(i)
-		if strings.HasPrefix(f.Name, "XXX_") {
+		if strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
 		mergeAny(out.Field(i), in.Field(i), false, sprop.Prop[i])
@@ -90,13 +90,13 @@ func mergeStruct(out, in reflect.Value) {
 		}
 	}
 
-	uf := in.FieldByName("XXX_unrecognized")
+	uf := unknownFieldsValue(in)
 	if !uf.IsValid() {
 		return
 	}
 	uin := uf.Bytes()
 	if len(uin) > 0 {
-		out.FieldByName("XXX_unrecognized").SetBytes(append([]byte(nil), uin...))
+		unknownFieldsValue(out).SetBytes(append([]byte(nil), uin...))
 	}
 }
 
diff --git a/proto/discard.go b/proto/discard.go
index c53d4b177c..8e61be3648 100644
--- a/proto/discard.go
+++ b/proto/discard.go
@@ -127,11 +127,11 @@ func (di *discardInfo) computeDiscardInfo() {
 
 	for i := 0; i < n; i++ {
 		f := t.Field(i)
-		if strings.HasPrefix(f.Name, "XXX_") {
+		if strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
 
-		dfi := discardFieldInfo{field: toField(&f)}
+		dfi := discardFieldInfo{field: toField(&f, nil)}
 		tf := f.Type
 
 		// Unwrap tf to get its most basic type.
@@ -219,12 +219,19 @@ func (di *discardInfo) computeDiscardInfo() {
 		di.fields = append(di.fields, dfi)
 	}
 
+	expFunc := exporterFunc(t)
 	di.unrecognized = invalidField
 	if f, ok := t.FieldByName("XXX_unrecognized"); ok {
 		if f.Type != reflect.TypeOf([]byte{}) {
 			panic("expected XXX_unrecognized to be of type []byte")
 		}
-		di.unrecognized = toField(&f)
+		di.unrecognized = toField(&f, nil)
+	}
+	if f, ok := t.FieldByName("unknownFields"); ok {
+		if f.Type != reflect.TypeOf([]byte{}) {
+			panic("expected unknownFields to be of type []byte")
+		}
+		di.unrecognized = toField(&f, expFunc)
 	}
 
 	atomic.StoreInt32(&di.initialized, 1)
@@ -243,7 +250,7 @@ func discardLegacy(m Message) {
 
 	for i := 0; i < v.NumField(); i++ {
 		f := t.Field(i)
-		if strings.HasPrefix(f.Name, "XXX_") {
+		if strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
 		vf := v.Field(i)
@@ -308,9 +315,9 @@ func discardLegacy(m Message) {
 		}
 	}
 
-	if vf := v.FieldByName("XXX_unrecognized"); vf.IsValid() {
+	if vf := unknownFieldsValue(v); vf.IsValid() {
 		if vf.Type() != reflect.TypeOf([]byte{}) {
-			panic("expected XXX_unrecognized to be of type []byte")
+			panic("expected unknown fields to be of type []byte")
 		}
 		vf.Set(reflect.ValueOf([]byte(nil)))
 	}
diff --git a/proto/equal.go b/proto/equal.go
index ceebce79f0..b2a69e15ed 100644
--- a/proto/equal.go
+++ b/proto/equal.go
@@ -72,7 +72,7 @@ func equalStruct(v1, v2 reflect.Value) bool {
 	sprop := GetProperties(v1.Type())
 	for i := 0; i < v1.NumField(); i++ {
 		f := v1.Type().Field(i)
-		if strings.HasPrefix(f.Name, "XXX_") {
+		if strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
 		f1, f2 := v1.Field(i), v2.Field(i)
@@ -91,8 +91,8 @@ func equalStruct(v1, v2 reflect.Value) bool {
 		}
 	}
 
-	if em1 := v1.FieldByName("XXX_InternalExtensions"); em1.IsValid() {
-		em2 := v2.FieldByName("XXX_InternalExtensions")
+	if em1 := extensionFieldsValue(v1); em1.IsValid() {
+		em2 := extensionFieldsValue(v2)
 		m1 := extensionFieldsOf(em1.Addr().Interface())
 		m2 := extensionFieldsOf(em2.Addr().Interface())
 		if !equalExtensions(v1.Type(), m1, m2) {
@@ -100,23 +100,15 @@ func equalStruct(v1, v2 reflect.Value) bool {
 		}
 	}
 
-	if em1 := v1.FieldByName("XXX_extensions"); em1.IsValid() {
-		em2 := v2.FieldByName("XXX_extensions")
-		m1 := extensionFieldsOf(em1.Addr().Interface())
-		m2 := extensionFieldsOf(em2.Addr().Interface())
-		if !equalExtensions(v1.Type(), m1, m2) {
+	if uf := unknownFieldsValue(v1); uf.IsValid() {
+		u1 := uf.Bytes()
+		u2 := unknownFieldsValue(v2).Bytes()
+		if !bytes.Equal(u1, u2) {
 			return false
 		}
 	}
 
-	uf := v1.FieldByName("XXX_unrecognized")
-	if !uf.IsValid() {
-		return true
-	}
-
-	u1 := uf.Bytes()
-	u2 := v2.FieldByName("XXX_unrecognized").Bytes()
-	return bytes.Equal(u1, u2)
+	return true
 }
 
 // v1 and v2 are known to have the same type.
diff --git a/proto/extensions.go b/proto/extensions.go
index a85ee41a57..adf24b9ea0 100644
--- a/proto/extensions.go
+++ b/proto/extensions.go
@@ -69,11 +69,8 @@ func extendable(p interface{}) (*extensionMap, error) {
 		v := reflect.ValueOf(p)
 		if v.Kind() == reflect.Ptr && !v.IsNil() {
 			v = v.Elem()
-			if v := v.FieldByName("XXX_InternalExtensions"); v.IsValid() {
-				return extensionFieldsOf(v.Addr().Interface()), nil
-			}
-			if v := v.FieldByName("XXX_extensions"); v.IsValid() {
-				return extensionFieldsOf(v.Addr().Interface()), nil
+			if vf := extensionFieldsValue(v); vf.IsValid() {
+				return extensionFieldsOf(vf.Addr().Interface()), nil
 			}
 		}
 	}
@@ -102,7 +99,7 @@ func SetRawExtension(base Message, id int32, b []byte) {
 	if !v.IsValid() || v.Kind() != reflect.Ptr || v.IsNil() || v.Elem().Kind() != reflect.Struct {
 		return
 	}
-	v = v.Elem().FieldByName("XXX_unrecognized")
+	v = unknownFieldsValue(v.Elem())
 	if !v.IsValid() {
 		return
 	}
@@ -208,7 +205,7 @@ func HasExtension(pb Message, extension *ExtensionDesc) bool {
 	}
 
 	// Check whether this field exists in raw form.
-	unrecognized := reflect.ValueOf(pb).Elem().FieldByName("XXX_unrecognized")
+	unrecognized := unknownFieldsValue(reflect.ValueOf(pb).Elem())
 	fnum := protoreflect.FieldNumber(extension.Field)
 	for b := unrecognized.Bytes(); len(b) > 0; {
 		got, _, n := wire.ConsumeField(b)
@@ -250,7 +247,7 @@ func GetExtension(pb Message, extension *ExtensionDesc) (interface{}, error) {
 		return nil, err
 	}
 
-	unrecognized := reflect.ValueOf(pb).Elem().FieldByName("XXX_unrecognized")
+	unrecognized := unknownFieldsValue(reflect.ValueOf(pb).Elem())
 	var out []byte
 	fnum := protoreflect.FieldNumber(extension.Field)
 	for b := unrecognized.Bytes(); len(b) > 0; {
@@ -416,7 +413,7 @@ func ExtensionDescs(pb Message) ([]*ExtensionDesc, error) {
 		return true
 	})
 
-	unrecognized := reflect.ValueOf(pb).Elem().FieldByName("XXX_unrecognized")
+	unrecognized := unknownFieldsValue(reflect.ValueOf(pb).Elem())
 	if b := unrecognized.Bytes(); len(b) > 0 {
 		fieldNums := make(map[int32]bool)
 		for len(b) > 0 {
diff --git a/proto/extensions_test.go b/proto/extensions_test.go
index 044aaf4a64..e06812a0f1 100644
--- a/proto/extensions_test.go
+++ b/proto/extensions_test.go
@@ -268,47 +268,53 @@ func TestGetExtensionDefaults(t *testing.T) {
 		{pb.E_DefaultEnum, setEnum, pb.DefaultsMessage_ONE},
 	}
 
-	checkVal := func(test testcase, msg *pb.DefaultsMessage, valWant interface{}) error {
-		val, err := proto.GetExtension(msg, test.ext)
-		if err != nil {
-			if valWant != nil {
-				return fmt.Errorf("GetExtension(): %s", err)
-			}
-			if want := proto.ErrMissingExtension; err != want {
-				return fmt.Errorf("Unexpected error: got %v, want %v", err, want)
+	checkVal := func(t *testing.T, name string, test testcase, msg *pb.DefaultsMessage, valWant interface{}) {
+		t.Run(name, func(t *testing.T) {
+			val, err := proto.GetExtension(msg, test.ext)
+			if err != nil {
+				if valWant != nil {
+					t.Errorf("GetExtension(): %s", err)
+					return
+				}
+				if want := proto.ErrMissingExtension; err != want {
+					t.Errorf("Unexpected error: got %v, want %v", err, want)
+					return
+				}
+				return
 			}
-			return nil
-		}
-
-		// All proto2 extension values are either a pointer to a value or a slice of values.
-		ty := reflect.TypeOf(val)
-		tyWant := reflect.TypeOf(test.ext.ExtensionType)
-		if got, want := ty, tyWant; got != want {
-			return fmt.Errorf("unexpected reflect.TypeOf(): got %v want %v", got, want)
-		}
-		tye := ty.Elem()
-		tyeWant := tyWant.Elem()
-		if got, want := tye, tyeWant; got != want {
-			return fmt.Errorf("unexpected reflect.TypeOf().Elem(): got %v want %v", got, want)
-		}
 
-		// Check the name of the type of the value.
-		// If it is an enum it will be type int32 with the name of the enum.
-		if got, want := tye.Name(), tye.Name(); got != want {
-			return fmt.Errorf("unexpected reflect.TypeOf().Elem().Name(): got %v want %v", got, want)
-		}
+			// All proto2 extension values are either a pointer to a value or a slice of values.
+			ty := reflect.TypeOf(val)
+			tyWant := reflect.TypeOf(test.ext.ExtensionType)
+			if got, want := ty, tyWant; got != want {
+				t.Errorf("unexpected reflect.TypeOf(): got %v want %v", got, want)
+				return
+			}
+			tye := ty.Elem()
+			tyeWant := tyWant.Elem()
+			if got, want := tye, tyeWant; got != want {
+				t.Errorf("unexpected reflect.TypeOf().Elem(): got %v want %v", got, want)
+				return
+			}
 
-		// Check that value is what we expect.
-		// If we have a pointer in val, get the value it points to.
-		valExp := val
-		if ty.Kind() == reflect.Ptr {
-			valExp = reflect.ValueOf(val).Elem().Interface()
-		}
-		if got, want := valExp, valWant; !reflect.DeepEqual(got, want) {
-			return fmt.Errorf("unexpected reflect.DeepEqual(): got %v want %v", got, want)
-		}
+			// Check the name of the type of the value.
+			// If it is an enum it will be type int32 with the name of the enum.
+			if got, want := tye.Name(), tye.Name(); got != want {
+				t.Errorf("unexpected reflect.TypeOf().Elem().Name(): got %v want %v", got, want)
+				return
+			}
 
-		return nil
+			// Check that value is what we expect.
+			// If we have a pointer in val, get the value it points to.
+			valExp := val
+			if ty.Kind() == reflect.Ptr {
+				valExp = reflect.ValueOf(val).Elem().Interface()
+			}
+			if got, want := valExp, valWant; !reflect.DeepEqual(got, want) {
+				t.Errorf("unexpected reflect.DeepEqual(): got %v want %v", got, want)
+				return
+			}
+		})
 	}
 
 	setTo := func(test testcase) interface{} {
@@ -326,27 +332,18 @@ func TestGetExtensionDefaults(t *testing.T) {
 		name := test.ext.Name
 
 		// Check the initial value.
-		if err := checkVal(test, msg, test.def); err != nil {
-			t.Errorf("%s: %v", name, err)
-		}
+		checkVal(t, name+"/initial", test, msg, test.def)
 
 		// Set the per-type value and check value.
-		name = fmt.Sprintf("%s (set to %T %v)", name, test.want, test.want)
 		if err := proto.SetExtension(msg, test.ext, setTo(test)); err != nil {
 			t.Errorf("%s: SetExtension(): %v", name, err)
 			continue
 		}
-		if err := checkVal(test, msg, test.want); err != nil {
-			t.Errorf("%s: %v", name, err)
-			continue
-		}
+		checkVal(t, name+"/set", test, msg, test.want)
 
 		// Set and check the value.
-		name += " (cleared)"
 		proto.ClearExtension(msg, test.ext)
-		if err := checkVal(test, msg, test.def); err != nil {
-			t.Errorf("%s: %v", name, err)
-		}
+		checkVal(t, name+"/cleared", test, msg, test.def)
 	}
 }
 
diff --git a/proto/lib.go b/proto/lib.go
index c8afe8a541..ada7b33fee 100644
--- a/proto/lib.go
+++ b/proto/lib.go
@@ -15,7 +15,9 @@ import (
 	"strconv"
 	"sync"
 
+	protoV2 "google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/runtime/protoiface"
+	"google.golang.org/protobuf/runtime/protoimpl"
 )
 
 // requiredNotSetError is an error type returned by either Marshal or Unmarshal.
@@ -95,6 +97,72 @@ type (
 	}
 )
 
+// oneofWrappers returns a list of oneof wrappers for t,
+// which must be a named struct type.
+func oneofWrappers(t reflect.Type) []interface{} {
+	var oos []interface{}
+	switch m := reflect.Zero(reflect.PtrTo(t)).Interface().(type) {
+	case oneofFuncsIface:
+		_, _, _, oos = m.XXX_OneofFuncs()
+	case oneofWrappersIface:
+		oos = m.XXX_OneofWrappers()
+	case protoV2.Message:
+		if m, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *protoimpl.MessageInfo }); ok {
+			oos = m.ProtoMessageInfo().OneofWrappers
+		}
+	}
+	return oos
+}
+
+// unknownFieldsValue retrieves the value for unknown fields from v,
+// which must be a name struct type.
+func unknownFieldsValue(v reflect.Value) reflect.Value {
+	if vf := v.FieldByName("XXX_unrecognized"); vf.IsValid() {
+		return vf
+	}
+	if vf := fieldByName(v, "unknownFields"); vf.IsValid() {
+		return vf
+	}
+	return reflect.Value{}
+}
+
+// extensionFieldsValue retrieves the value for extension fields from v,
+// which must be a name struct type.
+func extensionFieldsValue(v reflect.Value) reflect.Value {
+	if vf := v.FieldByName("XXX_InternalExtensions"); vf.IsValid() {
+		return vf
+	}
+	if vf := v.FieldByName("XXX_extensions"); vf.IsValid() {
+		return vf
+	}
+	if vf := fieldByName(v, "extensionFields"); vf.IsValid() {
+		return vf
+	}
+	return reflect.Value{}
+}
+
+// exporterFunc retrieves the field exporter function for t,
+// which must be a named struct type.
+func exporterFunc(t reflect.Type) func(interface{}, int) interface{} {
+	if m, ok := reflect.Zero(reflect.PtrTo(t)).Interface().(protoV2.Message); ok {
+		if m, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *protoimpl.MessageInfo }); ok {
+			return m.ProtoMessageInfo().Exporter
+		}
+	}
+	return nil
+}
+
+// isMessageSet determines whether t is a MessageSet message,
+// where t must be a named struct type.
+func isMessageSet(t reflect.Type) bool {
+	if m, ok := reflect.Zero(reflect.PtrTo(t)).Interface().(protoV2.Message); ok {
+		md := m.ProtoReflect().Descriptor()
+		xmd, ok := md.(interface{ IsMessageSet() bool })
+		return ok && xmd.IsMessageSet()
+	}
+	return false
+}
+
 // A Buffer is a buffer manager for marshaling and unmarshaling
 // protocol buffers.  It may be reused between invocations to
 // reduce memory usage.  It is not necessary to use a Buffer;
diff --git a/proto/message_set.go b/proto/message_set.go
index 8626382a2b..201030d467 100644
--- a/proto/message_set.go
+++ b/proto/message_set.go
@@ -122,7 +122,7 @@ func unmarshalMessageSet(buf []byte, mi Message, exts interface{}) error {
 	if err := Unmarshal(buf, ms); err != nil {
 		return err
 	}
-	unrecognized := reflect.ValueOf(mi).Elem().FieldByName("XXX_unrecognized").Addr().Interface().(*[]byte)
+	unrecognized := unknownFieldsValue(reflect.ValueOf(mi).Elem()).Addr().Interface().(*[]byte)
 
 	for _, item := range ms.Item {
 		id := protoreflect.FieldNumber(*item.TypeId)
diff --git a/proto/pointer_reflect.go b/proto/pointer_reflect.go
index 5ee1a0a91d..0b764bc682 100644
--- a/proto/pointer_reflect.go
+++ b/proto/pointer_reflect.go
@@ -13,6 +13,8 @@ package proto
 import (
 	"reflect"
 	"sync"
+	"unicode"
+	"unicode/utf8"
 )
 
 const unsafeAllowed = false
@@ -20,21 +22,35 @@ const unsafeAllowed = false
 // A field identifies a field in a struct, accessible from a pointer.
 // In this implementation, a field is identified by the sequence of field indices
 // passed to reflect's FieldByIndex.
-type field []int
+type field struct {
+	index  int
+	export exporter
+}
+
+type exporter = func(interface{}, int) interface{}
 
 // toField returns a field equivalent to the given reflect field.
-func toField(f *reflect.StructField) field {
-	return f.Index
+func toField(f *reflect.StructField, x exporter) field {
+	if len(f.Index) != 1 {
+		panic("embedded structs are not supported")
+	}
+	if f.PkgPath == "" {
+		return field{index: f.Index[0]} // field is already exported
+	}
+	if x == nil {
+		panic("exporter must be provided for unexported field: " + f.Name)
+	}
+	return field{index: f.Index[0], export: x}
 }
 
 // invalidField is an invalid field identifier.
-var invalidField = field(nil)
+var invalidField = field{index: -1}
 
 // zeroField is a noop when calling pointer.offset.
-var zeroField = field([]int{})
+var zeroField = field{index: 0}
 
 // IsValid reports whether the field identifier is valid.
-func (f field) IsValid() bool { return f != nil }
+func (f field) IsValid() bool { return f.index >= 0 }
 
 // The pointer type is for the table-driven decoder.
 // The implementation here uses a reflect.Value of pointer type to
@@ -70,7 +86,12 @@ func valToPointer(v reflect.Value) pointer {
 // offset converts from a pointer to a structure to a pointer to
 // one of its fields.
 func (p pointer) offset(f field) pointer {
-	return pointer{v: p.v.Elem().FieldByIndex(f).Addr()}
+	if f.export != nil {
+		if v := reflect.ValueOf(f.export(p.v.Interface(), f.index)); v.IsValid() {
+			return pointer{v: v}
+		}
+	}
+	return pointer{v: p.v.Elem().Field(f.index).Addr()}
 }
 
 func (p pointer) isNil() bool {
@@ -331,3 +352,20 @@ func atomicStoreDiscardInfo(p **discardInfo, v *discardInfo) {
 }
 
 var atomicLock sync.Mutex
+
+// fieldByName is equivalent to reflect.Value.FieldByName, but is able to
+// descend into unexported fields for prop
+func fieldByName(v reflect.Value, s string) reflect.Value {
+	if r, _ := utf8.DecodeRuneInString(s); unicode.IsUpper(r) {
+		return v.FieldByName(s)
+	}
+	t := v.Type()
+	if x := exporterFunc(t); x != nil {
+		sf, ok := t.FieldByName(s)
+		if ok {
+			vi := x(v.Addr().Interface(), sf.Index[0])
+			return reflect.ValueOf(vi).Elem()
+		}
+	}
+	return v.FieldByName(s)
+}
diff --git a/proto/pointer_unsafe.go b/proto/pointer_unsafe.go
index 52f1c92b55..20269f45a8 100644
--- a/proto/pointer_unsafe.go
+++ b/proto/pointer_unsafe.go
@@ -11,6 +11,8 @@ package proto
 import (
 	"reflect"
 	"sync/atomic"
+	"unicode"
+	"unicode/utf8"
 	"unsafe"
 )
 
@@ -20,8 +22,10 @@ const unsafeAllowed = true
 // In this implementation, a field is identified by its byte offset from the start of the struct.
 type field uintptr
 
+type exporter = func(interface{}, int) interface{}
+
 // toField returns a field equivalent to the given reflect field.
-func toField(f *reflect.StructField) field {
+func toField(f *reflect.StructField, x exporter) field {
 	return field(f.Offset)
 }
 
@@ -284,3 +288,16 @@ func atomicLoadDiscardInfo(p **discardInfo) *discardInfo {
 func atomicStoreDiscardInfo(p **discardInfo, v *discardInfo) {
 	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(p)), unsafe.Pointer(v))
 }
+
+// fieldByName is equivalent to reflect.Value.FieldByName, but is able to
+// descend into unexported fields for prop
+func fieldByName(v reflect.Value, s string) reflect.Value {
+	if r, _ := utf8.DecodeRuneInString(s); unicode.IsUpper(r) {
+		return v.FieldByName(s)
+	}
+	sf, ok := v.Type().FieldByName(s)
+	if !ok {
+		return reflect.Value{}
+	}
+	return reflect.NewAt(sf.Type, unsafe.Pointer(v.UnsafeAddr()+sf.Offset)).Elem()
+}
diff --git a/proto/properties.go b/proto/properties.go
index 6f15aeb839..88f6bb72f1 100644
--- a/proto/properties.go
+++ b/proto/properties.go
@@ -209,16 +209,9 @@ func newProperties(t reflect.Type) *StructProperties {
 	}
 
 	// Construct a mapping of oneof field names to properties.
-	var oneofWrappers []interface{}
-	if fn, ok := reflect.PtrTo(t).MethodByName("XXX_OneofFuncs"); ok {
-		oneofWrappers = fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[3].Interface().([]interface{})
-	}
-	if fn, ok := reflect.PtrTo(t).MethodByName("XXX_OneofWrappers"); ok {
-		oneofWrappers = fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))})[0].Interface().([]interface{})
-	}
-	if len(oneofWrappers) > 0 {
+	if oneofImplementors := oneofWrappers(t); len(oneofImplementors) > 0 {
 		prop.OneofTypes = make(map[string]*OneofProperties)
-		for _, wrapper := range oneofWrappers {
+		for _, wrapper := range oneofImplementors {
 			p := &OneofProperties{
 				Type: reflect.ValueOf(wrapper).Type(), // *T
 				Prop: new(Properties),
diff --git a/proto/table_marshal.go b/proto/table_marshal.go
index c3b581de3b..f6ac7f5403 100644
--- a/proto/table_marshal.go
+++ b/proto/table_marshal.go
@@ -297,37 +297,37 @@ func (u *marshalInfo) computeMarshalInfo() {
 		return
 	}
 
-	// get oneof implementers
-	var oneofImplementers []interface{}
-	switch m := reflect.Zero(reflect.PtrTo(t)).Interface().(type) {
-	case oneofFuncsIface:
-		_, _, _, oneofImplementers = m.XXX_OneofFuncs()
-	case oneofWrappersIface:
-		oneofImplementers = m.XXX_OneofWrappers()
-	}
+	oneofImplementers := oneofWrappers(t)
+	u.messageset = isMessageSet(t)
+	expFunc := exporterFunc(t)
 
 	n := t.NumField()
 
-	// deal with XXX fields first
+	// deal with XXX and unexported fields first.
 	for i := 0; i < t.NumField(); i++ {
 		f := t.Field(i)
-		if !strings.HasPrefix(f.Name, "XXX_") {
+		if !strings.HasPrefix(f.Name, "XXX_") && f.PkgPath == "" {
 			continue
 		}
 		switch f.Name {
 		case "XXX_sizecache":
-			u.sizecache = toField(&f)
+			u.sizecache = toField(&f, nil)
 		case "XXX_unrecognized":
-			u.unrecognized = toField(&f)
+			u.unrecognized = toField(&f, nil)
 		case "XXX_InternalExtensions":
-			u.extensions = toField(&f)
-			u.messageset = f.Tag.Get("protobuf_messageset") == "1"
+			u.extensions = toField(&f, nil)
+			if f.Tag.Get("protobuf_messageset") == "1" {
+				u.messageset = true
+			}
 		case "XXX_extensions":
-			u.v1extensions = toField(&f)
-		case "XXX_NoUnkeyedLiteral":
-			// nothing to do
-		default:
-			panic("unknown XXX field: " + f.Name)
+			u.v1extensions = toField(&f, nil)
+
+		case "sizeCache":
+			u.sizecache = toField(&f, expFunc)
+		case "unknownFields":
+			u.unrecognized = toField(&f, expFunc)
+		case "extensionFields":
+			u.extensions = toField(&f, expFunc)
 		}
 		n--
 	}
@@ -338,7 +338,7 @@ func (u *marshalInfo) computeMarshalInfo() {
 	for i, j := 0, 0; i < t.NumField(); i++ {
 		f := t.Field(i)
 
-		if strings.HasPrefix(f.Name, "XXX_") {
+		if strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
 		field := &fields[j]
@@ -438,7 +438,7 @@ func (fi *marshalFieldInfo) computeMarshalFieldInfo(f *reflect.StructField) {
 }
 
 func (fi *marshalFieldInfo) computeOneofFieldInfo(f *reflect.StructField, oneofImplementers []interface{}) {
-	fi.field = toField(f)
+	fi.field = toField(f, nil)
 	fi.wiretag = math.MaxInt32 // Use a large tag number, make oneofs sorted at the end. This tag will not appear on the wire.
 	fi.isPointer = true
 	fi.sizer, fi.marshaler = makeOneOfMarshaler(fi, f)
@@ -486,7 +486,7 @@ func wiretype(encoding string) uint64 {
 
 // setTag fills up the tag (in wire format) and its size in the info of a field.
 func (fi *marshalFieldInfo) setTag(f *reflect.StructField, tag int, wt uint64) {
-	fi.field = toField(f)
+	fi.field = toField(f, nil)
 	fi.wiretag = uint64(tag)<<3 | wt
 	fi.tagsize = SizeVarint(uint64(tag) << 3)
 }
diff --git a/proto/table_merge.go b/proto/table_merge.go
index 3565efbda7..04f9a90db4 100644
--- a/proto/table_merge.go
+++ b/proto/table_merge.go
@@ -141,11 +141,11 @@ func (mi *mergeInfo) computeMergeInfo() {
 	props := GetProperties(t)
 	for i := 0; i < n; i++ {
 		f := t.Field(i)
-		if strings.HasPrefix(f.Name, "XXX_") {
+		if strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
 
-		mfi := mergeFieldInfo{field: toField(&f)}
+		mfi := mergeFieldInfo{field: toField(&f, nil)}
 		tf := f.Type
 
 		// As an optimization, we can avoid the merge function call cost
@@ -611,12 +611,19 @@ func (mi *mergeInfo) computeMergeInfo() {
 		mi.fields = append(mi.fields, mfi)
 	}
 
+	expFunc := exporterFunc(t)
 	mi.unrecognized = invalidField
 	if f, ok := t.FieldByName("XXX_unrecognized"); ok {
 		if f.Type != reflect.TypeOf([]byte{}) {
 			panic("expected XXX_unrecognized to be of type []byte")
 		}
-		mi.unrecognized = toField(&f)
+		mi.unrecognized = toField(&f, nil)
+	}
+	if f, ok := t.FieldByName("unknownFields"); ok {
+		if f.Type != reflect.TypeOf([]byte{}) {
+			panic("expected unknownFields to be of type []byte")
+		}
+		mi.unrecognized = toField(&f, expFunc)
 	}
 
 	atomic.StoreInt32(&mi.initialized, 1)
diff --git a/proto/table_unmarshal.go b/proto/table_unmarshal.go
index 152ab79fde..64bf90928b 100644
--- a/proto/table_unmarshal.go
+++ b/proto/table_unmarshal.go
@@ -312,6 +312,10 @@ func (u *unmarshalInfo) computeUnmarshalInfo() {
 	}
 	var oneofFields []oneofField
 
+	oneofImplementers := oneofWrappers(t)
+	u.isMessageSet = isMessageSet(t)
+	expFunc := exporterFunc(t)
+
 	for i := 0; i < n; i++ {
 		f := t.Field(i)
 		if f.Name == "XXX_unrecognized" {
@@ -319,7 +323,7 @@ func (u *unmarshalInfo) computeUnmarshalInfo() {
 			if f.Type != reflect.TypeOf(([]byte)(nil)) {
 				panic("bad type for XXX_unrecognized field: " + f.Type.Name())
 			}
-			u.unrecognized = toField(&f)
+			u.unrecognized = toField(&f, nil)
 			continue
 		}
 		if f.Name == "XXX_InternalExtensions" {
@@ -327,7 +331,7 @@ func (u *unmarshalInfo) computeUnmarshalInfo() {
 			if f.Type != reflect.TypeOf(XXX_InternalExtensions{}) {
 				panic("bad type for XXX_InternalExtensions field: " + f.Type.Name())
 			}
-			u.extensions = toField(&f)
+			u.extensions = toField(&f, nil)
 			if f.Tag.Get("protobuf_messageset") == "1" {
 				u.isMessageSet = true
 			}
@@ -338,16 +342,31 @@ func (u *unmarshalInfo) computeUnmarshalInfo() {
 			if f.Type != reflect.TypeOf((map[int32]Extension)(nil)) {
 				panic("bad type for XXX_extensions field: " + f.Type.Name())
 			}
-			u.oldExtensions = toField(&f)
+			u.oldExtensions = toField(&f, nil)
 			continue
 		}
-		if f.Name == "XXX_NoUnkeyedLiteral" || f.Name == "XXX_sizecache" {
+		if f.Name == "unknownFields" {
+			if f.Type != reflect.TypeOf(([]byte)(nil)) {
+				panic("bad type for unknownFields field: " + f.Type.Name())
+			}
+			u.unrecognized = toField(&f, expFunc)
+			continue
+		}
+		if f.Name == "extensionFields" {
+			if f.Type != reflect.TypeOf(XXX_InternalExtensions{}) {
+				panic("bad type for extensionFields field: " + f.Type.Name())
+			}
+			u.extensions = toField(&f, expFunc)
+			continue
+		}
+
+		if strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
 
 		oneof := f.Tag.Get("protobuf_oneof")
 		if oneof != "" {
-			oneofFields = append(oneofFields, oneofField{f.Type, toField(&f)})
+			oneofFields = append(oneofFields, oneofField{f.Type, toField(&f, nil)})
 			// The rest of oneof processing happens below.
 			continue
 		}
@@ -384,17 +403,10 @@ func (u *unmarshalInfo) computeUnmarshalInfo() {
 		}
 
 		// Store the info in the correct slot in the message.
-		u.setTag(tag, toField(&f), unmarshal, reqMask, name)
+		u.setTag(tag, toField(&f, nil), unmarshal, reqMask, name)
 	}
 
 	// Find any types associated with oneof fields.
-	var oneofImplementers []interface{}
-	switch m := reflect.Zero(reflect.PtrTo(t)).Interface().(type) {
-	case oneofFuncsIface:
-		_, _, _, oneofImplementers = m.XXX_OneofFuncs()
-	case oneofWrappersIface:
-		oneofImplementers = m.XXX_OneofWrappers()
-	}
 	for _, v := range oneofImplementers {
 		tptr := reflect.TypeOf(v) // *Msg_X
 		typ := tptr.Elem()        // Msg_X
@@ -1846,7 +1858,7 @@ func makeUnmarshalMap(f *reflect.StructField) unmarshaler {
 // Note that this function will be called once for each case in the oneof.
 func makeUnmarshalOneof(typ, ityp reflect.Type, unmarshal unmarshaler) unmarshaler {
 	sf := typ.Field(0)
-	field0 := toField(&sf)
+	field0 := toField(&sf, nil)
 	return func(b []byte, f pointer, w int) ([]byte, error) {
 		// Allocate holder for value.
 		v := reflect.New(typ)
diff --git a/proto/text.go b/proto/text.go
index ef8735f116..40f7912b0c 100644
--- a/proto/text.go
+++ b/proto/text.go
@@ -19,6 +19,7 @@ import (
 	"sort"
 	"strings"
 
+	protoV2 "google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/reflect/protoreflect"
 )
 
@@ -165,11 +166,14 @@ func requiresQuotes(u string) bool {
 
 // isAny reports whether sv is a google.protobuf.Any message
 func isAny(sv reflect.Value) bool {
-	type wkt interface {
-		XXX_WellKnownType() string
+	switch m := sv.Addr().Interface().(type) {
+	case interface{ XXX_WellKnownType() string }:
+		return m.XXX_WellKnownType() == "Any"
+	case protoV2.Message:
+		return m.ProtoReflect().Descriptor().FullName() == "google.protobuf.Any"
+	default:
+		return false
 	}
-	t, ok := sv.Addr().Interface().(wkt)
-	return ok && t.XXX_WellKnownType() == "Any"
 }
 
 // writeProto3Any writes an expanded google.protobuf.Any message.
@@ -236,23 +240,9 @@ func (tm *textMarshaler) writeStruct(w *textWriter, sv reflect.Value) error {
 	for i := 0; i < sv.NumField(); i++ {
 		fv := sv.Field(i)
 		props := sprops.Prop[i]
-		name := st.Field(i).Name
-
-		if name == "XXX_NoUnkeyedLiteral" {
-			continue
-		}
 
-		if strings.HasPrefix(name, "XXX_") {
-			// There are two XXX_ fields:
-			//   XXX_unrecognized []byte
-			//   XXX_extensions   map[int32]proto.Extension
-			// The first is handled here;
-			// the second is handled at the bottom of this function.
-			if name == "XXX_unrecognized" && !fv.IsNil() {
-				if err := writeUnknownStruct(w, fv.Interface().([]byte)); err != nil {
-					return err
-				}
-			}
+		f := st.Field(i)
+		if strings.HasPrefix(f.Name, "XXX_") || f.PkgPath != "" {
 			continue
 		}
 		if fv.Kind() == reflect.Ptr && fv.IsNil() {
@@ -420,6 +410,12 @@ func (tm *textMarshaler) writeStruct(w *textWriter, sv reflect.Value) error {
 		}
 	}
 
+	if fv := unknownFieldsValue(sv); !fv.IsNil() {
+		if err := writeUnknownStruct(w, fv.Interface().([]byte)); err != nil {
+			return err
+		}
+	}
+
 	// Extensions (the XXX_extensions field).
 	pv := sv.Addr()
 	if _, err := extendable(pv.Interface()); err == nil {
@@ -682,15 +678,20 @@ func (tm *textMarshaler) writeExtensions(w *textWriter, pv reflect.Value) error
 			return fmt.Errorf("failed getting extension: %v", err)
 		}
 
+		name := desc.Name
+		if strings.HasSuffix(name, ".message_set_extension") && isMessageSet(pv.Type().Elem()) {
+			name = strings.TrimSuffix(name, ".message_set_extension")
+		}
+
 		// Repeated extensions will appear as a slice.
 		if !isRepeatedExtension(desc) {
-			if err := tm.writeExtension(w, desc.Name, pb); err != nil {
+			if err := tm.writeExtension(w, name, pb); err != nil {
 				return err
 			}
 		} else {
 			v := reflect.ValueOf(pb)
 			for i := 0; i < v.Len(); i++ {
-				if err := tm.writeExtension(w, desc.Name, v.Index(i).Interface()); err != nil {
+				if err := tm.writeExtension(w, name, v.Index(i).Interface()); err != nil {
 					return err
 				}
 			}
diff --git a/proto/text_parser.go b/proto/text_parser.go
index 443f62707e..8fb9463a4b 100644
--- a/proto/text_parser.go
+++ b/proto/text_parser.go
@@ -525,6 +525,10 @@ func (p *textParser) readStruct(sv reflect.Value, terminator string) error {
 					desc = d
 					break
 				}
+				if strings.TrimSuffix(d.Name, ".message_set_extension") == extName && isMessageSet(st) {
+					desc = d
+					break
+				}
 			}
 			if desc == nil {
 				return p.errorf("unrecognized extension %q", extName)
diff --git a/protoc-gen-go/descriptor/descriptor.pb.go b/protoc-gen-go/descriptor/descriptor.pb.go
index 0e07d08624..c2fb216795 100644
--- a/protoc-gen-go/descriptor/descriptor.pb.go
+++ b/protoc-gen-go/descriptor/descriptor.pb.go
@@ -7,6 +7,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	descriptorpb "google.golang.org/protobuf/types/descriptorpb"
+	reflect "reflect"
 	sync "sync"
 )
 
@@ -199,8 +200,10 @@ func file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_i
 	if File_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto != nil {
 		return
 	}
+	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_golang_protobuf_protoc_gen_go_descriptor_descriptor_proto_rawDesc,
 			NumEnums:      0,
 			NumMessages:   0,
diff --git a/protoc-gen-go/plugin/plugin.pb.go b/protoc-gen-go/plugin/plugin.pb.go
index 5d88470c36..28c50931f3 100644
--- a/protoc-gen-go/plugin/plugin.pb.go
+++ b/protoc-gen-go/plugin/plugin.pb.go
@@ -7,6 +7,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	pluginpb "google.golang.org/protobuf/types/pluginpb"
+	reflect "reflect"
 	sync "sync"
 )
 
@@ -66,8 +67,10 @@ func file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_init() {
 	if File_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto != nil {
 		return
 	}
+	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_golang_protobuf_protoc_gen_go_plugin_plugin_proto_rawDesc,
 			NumEnums:      0,
 			NumMessages:   0,
diff --git a/ptypes/any/any.pb.go b/ptypes/any/any.pb.go
index d076aa2df9..96dc8e3f9f 100644
--- a/ptypes/any/any.pb.go
+++ b/ptypes/any/any.pb.go
@@ -7,6 +7,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	anypb "google.golang.org/protobuf/types/known/anypb"
+	reflect "reflect"
 	sync "sync"
 )
 
@@ -61,8 +62,10 @@ func file_github_com_golang_protobuf_ptypes_any_any_proto_init() {
 	if File_github_com_golang_protobuf_ptypes_any_any_proto != nil {
 		return
 	}
+	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_golang_protobuf_ptypes_any_any_proto_rawDesc,
 			NumEnums:      0,
 			NumMessages:   0,
diff --git a/ptypes/duration/duration.pb.go b/ptypes/duration/duration.pb.go
index 8dc1778321..ea23997333 100644
--- a/ptypes/duration/duration.pb.go
+++ b/ptypes/duration/duration.pb.go
@@ -7,6 +7,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	durationpb "google.golang.org/protobuf/types/known/durationpb"
+	reflect "reflect"
 	sync "sync"
 )
 
@@ -62,8 +63,10 @@ func file_github_com_golang_protobuf_ptypes_duration_duration_proto_init() {
 	if File_github_com_golang_protobuf_ptypes_duration_duration_proto != nil {
 		return
 	}
+	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_golang_protobuf_ptypes_duration_duration_proto_rawDesc,
 			NumEnums:      0,
 			NumMessages:   0,
diff --git a/ptypes/empty/empty.pb.go b/ptypes/empty/empty.pb.go
index 890ab4ceff..b8022dc19e 100644
--- a/ptypes/empty/empty.pb.go
+++ b/ptypes/empty/empty.pb.go
@@ -7,6 +7,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	emptypb "google.golang.org/protobuf/types/known/emptypb"
+	reflect "reflect"
 	sync "sync"
 )
 
@@ -61,8 +62,10 @@ func file_github_com_golang_protobuf_ptypes_empty_empty_proto_init() {
 	if File_github_com_golang_protobuf_ptypes_empty_empty_proto != nil {
 		return
 	}
+	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_golang_protobuf_ptypes_empty_empty_proto_rawDesc,
 			NumEnums:      0,
 			NumMessages:   0,
diff --git a/ptypes/struct/struct.pb.go b/ptypes/struct/struct.pb.go
index 47e8fd776c..fae4ea1ed5 100644
--- a/ptypes/struct/struct.pb.go
+++ b/ptypes/struct/struct.pb.go
@@ -7,6 +7,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	structpb "google.golang.org/protobuf/types/known/structpb"
+	reflect "reflect"
 	sync "sync"
 )
 
@@ -77,8 +78,10 @@ func file_github_com_golang_protobuf_ptypes_struct_struct_proto_init() {
 	if File_github_com_golang_protobuf_ptypes_struct_struct_proto != nil {
 		return
 	}
+	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_golang_protobuf_ptypes_struct_struct_proto_rawDesc,
 			NumEnums:      0,
 			NumMessages:   0,
diff --git a/ptypes/timestamp/timestamp.pb.go b/ptypes/timestamp/timestamp.pb.go
index 32fe5b318c..4100c26384 100644
--- a/ptypes/timestamp/timestamp.pb.go
+++ b/ptypes/timestamp/timestamp.pb.go
@@ -7,6 +7,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	timestamppb "google.golang.org/protobuf/types/known/timestamppb"
+	reflect "reflect"
 	sync "sync"
 )
 
@@ -63,8 +64,10 @@ func file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_init() {
 	if File_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto != nil {
 		return
 	}
+	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_golang_protobuf_ptypes_timestamp_timestamp_proto_rawDesc,
 			NumEnums:      0,
 			NumMessages:   0,
diff --git a/ptypes/wrappers/wrappers.pb.go b/ptypes/wrappers/wrappers.pb.go
index dec0553be4..faeefe7923 100644
--- a/ptypes/wrappers/wrappers.pb.go
+++ b/ptypes/wrappers/wrappers.pb.go
@@ -7,6 +7,7 @@ import (
 	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
 	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
 	wrapperspb "google.golang.org/protobuf/types/known/wrapperspb"
+	reflect "reflect"
 	sync "sync"
 )
 
@@ -70,8 +71,10 @@ func file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_init() {
 	if File_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto != nil {
 		return
 	}
+	type x struct{}
 	out := protoimpl.TypeBuilder{
 		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: file_github_com_golang_protobuf_ptypes_wrappers_wrappers_proto_rawDesc,
 			NumEnums:      0,
 			NumMessages:   0,
diff --git a/test.bash b/test.bash
index a7351bfc60..bab98bc155 100755
--- a/test.bash
+++ b/test.bash
@@ -10,9 +10,17 @@ PASS="\x1b[32mPASS"
 FAIL="\x1b[31mFAIL"
 RESET="\x1b[0m"
 
-echo -e "${BOLD}go test${RESET}"
-RET_TEST=$((go test ./... && go test -tags use_golang_protobuf_v1 ./...) | egrep -v "^(ok|[?])\s+")
-if [[ ! -z "$RET_TEST" ]]; then echo "$RET_TEST"; echo; fi
+echo -e "${BOLD}go test -tags proto1_legacy ./...${RESET}"
+RET_TEST0=$(go test -tags proto1_legacy ./... | egrep -v "^(ok|[?])\s+")
+if [[ ! -z "$RET_TEST0" ]]; then echo "$RET_TEST0"; echo; fi
+
+echo -e "${BOLD}go test -tags use_golang_protobuf_v1 ./...${RESET}"
+RET_TEST1=$(go test -tags use_golang_protobuf_v1 ./... | egrep -v "^(ok|[?])\s+")
+if [[ ! -z "$RET_TEST1" ]]; then echo "$RET_TEST1"; echo; fi
+
+echo -e "${BOLD}go test -tags "use_golang_protobuf_v1 purego" ./...${RESET}"
+RET_TEST2=$(go test -tags "use_golang_protobuf_v1 purego" ./... | egrep -v "^(ok|[?])\s+")
+if [[ ! -z "$RET_TEST2" ]]; then echo "$RET_TEST2"; echo; fi
 
 echo -e "${BOLD}go generate${RESET}"
 RET_GEN=$(go run ./internal/cmd/generate-alias 2>&1)
@@ -30,7 +38,7 @@ echo -e "${BOLD}git ls-files${RESET}"
 RET_FILES=$(git ls-files --others --exclude-standard 2>&1)
 if [[ ! -z "$RET_FILES" ]]; then echo "$RET_FILES"; echo; fi
 
-if [[ ! -z "$RET_TEST" ]] || [[ ! -z "$RET_GEN" ]] || [ ! -z "$RET_FMT" ] || [[ ! -z "$RET_DIFF" ]] || [[ ! -z "$RET_FILES" ]]; then
+if [[ ! -z "$RET_TEST0" ]] || [[ ! -z "$RET_TEST1" ]] || [[ ! -z "$RET_TEST2" ]] || [[ ! -z "$RET_GEN" ]] || [ ! -z "$RET_FMT" ] || [[ ! -z "$RET_DIFF" ]] || [[ ! -z "$RET_FILES" ]]; then
 	echo -e "${FAIL}${RESET}"; exit 1
 else
 	echo -e "${PASS}${RESET}"; exit 0