diff --git a/build.sbt b/build.sbt
index f6cf3e3ac..2baf52182 100644
--- a/build.sbt
+++ b/build.sbt
@@ -3,9 +3,6 @@ import com.typesafe.tools.mima.core._
 import BuildHelper._
 import Dependencies._
 
-// Different version for compiler-plugin since >=3.8.0 is not binary
-// compatible with 3.7.x. When loaded inside SBT (which has its own old
-// version), the binary incompatibility surfaces.
 val protobufCompilerVersion = "3.12.2"
 
 val MimaPreviousVersion = "0.10.0"
@@ -345,6 +342,8 @@ lazy val e2eNoJava = (project in file("e2e-nojava"))
   .settings(e2eCommonSettings)
   .settings(
     Compile / PB.protocVersion := "-v" + versions.protobuf,
+    Compile / PB.protocOptions += "--experimental_allow_proto3_optional",
+    Compile / PB.generate := ((Compile / PB.generate) dependsOn (protocGenScalaUnix / Compile / assembly)).value,
     Compile / PB.targets := Seq(
       (
         PB.gens.plugin(
diff --git a/compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala b/compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala
index e0fa492bc..088ec8c52 100644
--- a/compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala
+++ b/compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala
@@ -58,7 +58,7 @@ class DescriptorImplicits(params: GeneratorParams, files: Seq[FileDescriptor]) {
       message <- file.allMessages if message.isSealedOneofType
     } yield SealedOneof(
       message,
-      message.getOneofs.get(0).getFields.asScala.map(_.getMessageType).toVector
+      message.getRealOneofs.get(0).getFields.asScala.map(_.getMessageType).toVector
     )
     new SealedOneofsCache(sealedOneof)
   }
@@ -185,7 +185,7 @@ class DescriptorImplicits(params: GeneratorParams, files: Seq[FileDescriptor]) {
   implicit class FieldDescriptorPimp(val fd: FieldDescriptor) {
     import NameUtils._
 
-    def containingOneOf: Option[OneofDescriptor] = Option(fd.getContainingOneof)
+    def containingOneOf: Option[OneofDescriptor] = Option(fd.getRealContainingOneof())
 
     def isInOneof: Boolean = containingOneOf.isDefined
 
@@ -230,7 +230,7 @@ class DescriptorImplicits(params: GeneratorParams, files: Seq[FileDescriptor]) {
 
     def oneOfTypeName: ScalaName = {
       assert(isInOneof)
-      fd.getContainingOneof.scalaType / upperScalaName
+      fd.getRealContainingOneof.scalaType / upperScalaName
     }
 
     def noBox =
@@ -241,12 +241,16 @@ class DescriptorImplicits(params: GeneratorParams, files: Seq[FileDescriptor]) {
     // Is this field boxed inside an Option in Scala. Equivalent, does the Java API
     // support hasX methods for this field.
     def supportsPresence: Boolean =
-      fd.isOptional && !fd.isInOneof && (!fd.getFile.isProto3 || fd.isMessage) &&
+      fd.isOptional && !fd.isInOneof && (!fd.getFile.isProto3 || fd.isMessage || fd
+        .toProto()
+        .getProto3Optional()) &&
         !noBox && !fd.isSealedOneofType
 
     // Is the Scala representation of this field a singular type.
     def isSingular =
-      fd.isRequired || (fd.getFile.isProto3 && !fd.isInOneof && fd.isOptional && !fd.isMessage) || (
+      fd.isRequired || (fd.getFile.isProto3 && !fd.isInOneof && fd.isOptional && !fd.isMessage && !fd
+        .toProto()
+        .getProto3Optional()) || (
         fd.isOptional && (noBox || (fd.isSealedOneofType && !fd.isInOneof))
       )
 
@@ -431,6 +435,7 @@ class DescriptorImplicits(params: GeneratorParams, files: Seq[FileDescriptor]) {
   }
 
   implicit class OneofDescriptorPimp(val oneof: OneofDescriptor) {
+
     def javaEnumName = {
       val name = NameUtils.snakeCaseToCamelCase(oneof.getName, true)
       s"get${name}Case"
@@ -476,8 +481,9 @@ class DescriptorImplicits(params: GeneratorParams, files: Seq[FileDescriptor]) {
 
     def sealedOneofStyle: SealedOneofStyle = {
       assert(isSealedOneofType)
-      if (message.getOneofs.asScala.exists(_.getName == "sealed_value")) SealedOneofStyle.Default
-      else if (message.getOneofs.asScala.exists(_.getName == "sealed_value_optional"))
+      if (message.getRealOneofs.asScala.exists(_.getName == "sealed_value"))
+        SealedOneofStyle.Default
+      else if (message.getRealOneofs.asScala.exists(_.getName == "sealed_value_optional"))
         SealedOneofStyle.Optional
       else throw new RuntimeException("Unexpected oneof style")
     }
@@ -485,7 +491,7 @@ class DescriptorImplicits(params: GeneratorParams, files: Seq[FileDescriptor]) {
     // every message that passes this filter must be a sealed oneof. The check that it actually
     // obeys the rules is done in ProtoValidation.
     def isSealedOneofType: Boolean = {
-      message.getOneofs.asScala
+      message.getRealOneofs.asScala
         .exists(o => o.getName == "sealed_value" || o.getName == "sealed_value_optional")
     }
 
diff --git a/compiler-plugin/src/main/scala/scalapb/compiler/ProtoValidation.scala b/compiler-plugin/src/main/scala/scalapb/compiler/ProtoValidation.scala
index 78a0b2d5e..aae04597e 100644
--- a/compiler-plugin/src/main/scala/scalapb/compiler/ProtoValidation.scala
+++ b/compiler-plugin/src/main/scala/scalapb/compiler/ProtoValidation.scala
@@ -49,7 +49,7 @@ class ProtoValidation(implicits: DescriptorImplicits) {
     m.getNestedTypes.asScala.foreach(validateMessage)
     m.getFields.asScala.foreach(validateField)
     if (m.isSealedOneofType) {
-      val oneof = m.getOneofs.get(0)
+      val oneof = m.getRealOneofs.get(0)
       if (m.getContainingType != null) {
         throw new GeneratorException(s"${m.getFullName}: sealed oneofs must be top-level messages")
       }
diff --git a/compiler-plugin/src/main/scala/scalapb/compiler/ProtobufGenerator.scala b/compiler-plugin/src/main/scala/scalapb/compiler/ProtobufGenerator.scala
index d48d5e504..88fedaf79 100644
--- a/compiler-plugin/src/main/scala/scalapb/compiler/ProtobufGenerator.scala
+++ b/compiler-plugin/src/main/scala/scalapb/compiler/ProtobufGenerator.scala
@@ -689,7 +689,7 @@ class ProtobufGenerator(
           annotations = annotations(field)
         )
     }
-    val oneOfFields = message.getOneofs.asScala.map { oneOf =>
+    val oneOfFields = message.getRealOneofs.asScala.map { oneOf =>
       val ctorDefaultValue: Option[String] =
         if (message.getFile.noDefaultValuesInConstructor) None
         else Some(oneOf.empty.fullNameWithMaybeRoot(message))
@@ -751,7 +751,7 @@ class ProtobufGenerator(
             fp.add(s"var __requiredFields$index: _root_.scala.Long = $bn")
         }
       }
-      .print(message.getOneofs.asScala)((printer, oneof) =>
+      .print(message.getRealOneofs.asScala)((printer, oneof) =>
         printer.add(s"var __${oneof.scalaName.name} = `_message__`.${oneof.scalaName.nameSymbol}")
       )
       .add(s"""var _done__ = false
@@ -846,7 +846,7 @@ class ProtobufGenerator(
       .add(s"$myFullScalaName(")
       .indent
       .addWithDelimiter(",")(
-        (message.fieldsWithoutOneofs ++ message.getOneofs.asScala).map {
+        (message.fieldsWithoutOneofs ++ message.getRealOneofs.asScala).map {
           case e: FieldDescriptor if e.isRepeated =>
             s"  ${e.scalaName.asSymbol} = __${e.scalaName}.result()"
           case e: FieldDescriptor =>
@@ -895,7 +895,7 @@ class ProtobufGenerator(
               else javaFieldToScala("javaPbSource", field)
             Seq(s"${field.scalaName.asSymbol} = $conversion")
         }
-        val oneOfs = message.getOneofs.asScala.map {
+        val oneOfs = message.getRealOneofs.asScala.map {
           case oneOf =>
             val head =
               s"${oneOf.scalaName.nameSymbol} = javaPbSource.${oneOf.javaEnumName}.getNumber match {"
@@ -976,7 +976,7 @@ class ProtobufGenerator(
               enclosingType = field.enclosingType
             )
         }
-        val oneOfs = message.getOneofs.asScala.map { oneOf =>
+        val oneOfs = message.getRealOneofs.asScala.map { oneOf =>
           val elems = oneOf.fields.map { field =>
             val value =
               s"__fieldsMap.get(scalaDescriptor.findFieldByNumber(${field.getNumber}).get)"
@@ -1022,7 +1022,7 @@ class ProtobufGenerator(
         case field if !field.isInOneof =>
           val default = defaultValueForDefaultInstance(field)
           s"${field.scalaName.asSymbol} = $default"
-      } ++ message.getOneofs.asScala.map { oneof =>
+      } ++ message.getRealOneofs.asScala.map { oneof =>
         s"${oneof.scalaName.nameSymbol} = ${oneof.empty.fullName}"
       })
       .outdent
@@ -1062,7 +1062,7 @@ class ProtobufGenerator(
               )
           }
       }
-      .print(message.getOneofs.asScala) {
+      .print(message.getRealOneofs.asScala) {
         case (printer, oneof) =>
           val oneofName = oneof.scalaName.nameSymbol
           printer
@@ -1353,7 +1353,7 @@ class ProtobufGenerator(
       .call(generateEnumCompanionForField(message))
       .call(generateDefaultInstance(message))
       .print(message.getEnumTypes.asScala)(printEnum)
-      .print(message.getOneofs.asScala)(printOneof)
+      .print(message.getRealOneofs.asScala)(printOneof)
       .print(message.nestedTypes)(printMessage)
       .print(message.getExtensions.asScala)(printExtension)
       .when(message.generateLenses)(generateMessageLens(message))
@@ -1457,7 +1457,7 @@ class ProtobufGenerator(
               )
             }
       }
-      .print(message.getOneofs.asScala) {
+      .print(message.getRealOneofs.asScala) {
         case (printer, oneof) =>
           printer.add(
             s"""def clear${oneof.scalaType.name}: ${message.scalaType.nameSymbol} = copy(${oneof.scalaName.nameSymbol} = ${oneof.empty
@@ -1736,22 +1736,17 @@ object ProtobufGenerator {
   def handleCodeGeneratorRequest(request: CodeGenRequest): CodeGenResponse = {
     parseParameters(request.parameter) match {
       case Right(params) =>
-        try {
-          val implicits = new DescriptorImplicits(params, request.allProtos)
-          val generator = new ProtobufGenerator(params, implicits)
-          val validator = new ProtoValidation(implicits)
-          validator.validateFiles(request.allProtos)
-          import implicits.FileDescriptorPimp
-          val files = request.filesToGenerate.flatMap { file =>
-            if (file.scalaOptions.getSingleFile)
-              generator.generateSingleScalaFileForFileDescriptor(file)
-            else generator.generateMultipleScalaFilesForFileDescriptor(file)
-          }
-          CodeGenResponse.succeed(files)
-        } catch {
-          case e: GeneratorException =>
-            CodeGenResponse.fail(e.message)
+        val implicits = new DescriptorImplicits(params, request.allProtos)
+        val generator = new ProtobufGenerator(params, implicits)
+        val validator = new ProtoValidation(implicits)
+        validator.validateFiles(request.allProtos)
+        import implicits.FileDescriptorPimp
+        val files = request.filesToGenerate.flatMap { file =>
+          if (file.scalaOptions.getSingleFile)
+            generator.generateSingleScalaFileForFileDescriptor(file)
+          else generator.generateMultipleScalaFilesForFileDescriptor(file)
         }
+        CodeGenResponse.succeed(files, Set(CodeGeneratorResponse.Feature.FEATURE_PROTO3_OPTIONAL))
       case Left(error) =>
         CodeGenResponse.fail(error)
     }
diff --git a/compiler-plugin/src/main/scala/scalapb/compiler/SealedOneofsGenerator.scala b/compiler-plugin/src/main/scala/scalapb/compiler/SealedOneofsGenerator.scala
index 07fdcfca3..2d59f0b6b 100644
--- a/compiler-plugin/src/main/scala/scalapb/compiler/SealedOneofsGenerator.scala
+++ b/compiler-plugin/src/main/scala/scalapb/compiler/SealedOneofsGenerator.scala
@@ -21,7 +21,7 @@ class SealedOneofsGenerator(message: Descriptor, implicits: DescriptorImplicits)
       val sealedOneofType = message.sealedOneofScalaType
       val sealedOneofName = message.sealedOneofTraitScalaType.nameSymbol
       val typeMapper      = s"_root_.scalapb.TypeMapper[${baseType}, ${sealedOneofType}]"
-      val oneof           = message.getOneofs.get(0)
+      val oneof           = message.getRealOneofs.get(0)
       val typeMapperName  = message.sealedOneofTypeMapper.name
 
       if (message.sealedOneofStyle != SealedOneofStyle.Optional) {
diff --git a/e2e-nojava/src/main/protobuf/proto3_presence.proto b/e2e-nojava/src/main/protobuf/proto3_presence.proto
new file mode 100644
index 000000000..3286f5f0c
--- /dev/null
+++ b/e2e-nojava/src/main/protobuf/proto3_presence.proto
@@ -0,0 +1,14 @@
+syntax = "proto3";
+
+package com.thesamet.proto.e2e;
+
+enum PEnum {
+  PENUM_UNKNOWN = 0;
+  PENUM_A = 1;
+}
+
+message Presence {
+  optional int32 i32 = 1;
+  optional PEnum penum = 2;
+  optional Presence presence = 3;
+}
diff --git a/e2e/src/main/protobuf/google/protobuf/unittest.proto b/e2e/src/main/protobuf/google/protobuf/unittest.proto
index 1582ed7f0..c8c1e414b 100644
--- a/e2e/src/main/protobuf/google/protobuf/unittest.proto
+++ b/e2e/src/main/protobuf/google/protobuf/unittest.proto
@@ -834,3 +834,6 @@ service TestService {
 message BarRequest  {}
 message BarResponse {}
 
+message TestMap {
+  map<int32, string> int32_to_string = 1;
+}
\ No newline at end of file
diff --git a/project/Dependencies.scala b/project/Dependencies.scala
index e04f14042..04bc8ba76 100644
--- a/project/Dependencies.scala
+++ b/project/Dependencies.scala
@@ -6,14 +6,14 @@ import Keys._
 object Dependencies {
   object versions {
     val grpc                    = "1.30.2"
-    val protobuf                = "3.11.4"
+    val protobuf                = "3.12.2"
     val utest                   = "0.7.4"
     val fastparse               = "2.3.0"
     val silencer                = "1.6.0"
     val collectionCompat        = "2.1.6"
     val coursier                = "2.0.0-RC6-21"
     val mockito                 = "3.2.0"
-    val protocGen               = "0.9.0-RC2"
+    val protocGen               = "0.9.0-RC3"
     val protocJar               = "3.11.4"
     val protobufRuntimeScala    = "0.8.6"
     val commonsCodec            = "1.14"
diff --git a/proptest/src/test/scala/GenTypes.scala b/proptest/src/test/scala/GenTypes.scala
index 59474929c..6265a4087 100644
--- a/proptest/src/test/scala/GenTypes.scala
+++ b/proptest/src/test/scala/GenTypes.scala
@@ -124,7 +124,7 @@ object GenTypes {
     val REPEATED = Value("repeated")
   }
 
-  case class FieldOptions(modifier: FieldModifier.Value, isPacked: Boolean)
+  case class FieldOptions(modifier: FieldModifier.Value, isPacked: Boolean, proto3Presence: Boolean)
 
   def genFieldModifier(allowRequired: Boolean): Gen[FieldModifier.Value] =
     if (allowRequired)
@@ -188,19 +188,28 @@ object GenTypes {
       protoSyntax: ProtoSyntax,
       inOneof: Boolean
   ): Gen[FieldOptions] =
-    if (inOneof) Gen.const(FieldOptions(FieldModifier.OPTIONAL, isPacked = false))
+    if (inOneof)
+      Gen.const(FieldOptions(FieldModifier.OPTIONAL, isPacked = false, proto3Presence = false))
     else
       fieldType match {
         case MessageReference(id) =>
-          genFieldModifier(allowRequired = protoSyntax.isProto2 && id < messageId)
-            .map(mod => FieldOptions(mod, isPacked = false))
-        case MapType(_, _) => Gen.const(FieldOptions(FieldModifier.REPEATED, isPacked = false))
+          for {
+            mod <- genFieldModifier(allowRequired = protoSyntax.isProto2 && id < messageId)
+            proto3Presence <- if (mod == FieldModifier.OPTIONAL && protoSyntax.isProto3)
+              Gen.oneOf(true, false)
+            else Gen.const(false)
+          } yield FieldOptions(mod, isPacked = false, proto3Presence = proto3Presence)
+        case MapType(_, _) =>
+          Gen.const(FieldOptions(FieldModifier.REPEATED, isPacked = false, proto3Presence = false))
         case _ =>
           for {
             mod <- genFieldModifier(allowRequired = protoSyntax.isProto2)
             packed <- if (fieldType.packable && mod == FieldModifier.REPEATED)
               Gen.oneOf(true, false)
             else Gen.const(false)
-          } yield FieldOptions(mod, isPacked = packed)
+            proto3Presence <- if (mod == FieldModifier.OPTIONAL && protoSyntax.isProto3)
+              Gen.oneOf(true, false)
+            else Gen.const(false)
+          } yield FieldOptions(mod, isPacked = packed, proto3Presence = proto3Presence)
       }
 }
diff --git a/proptest/src/test/scala/GraphGen.scala b/proptest/src/test/scala/GraphGen.scala
index 2d936cb98..f81c83108 100644
--- a/proptest/src/test/scala/GraphGen.scala
+++ b/proptest/src/test/scala/GraphGen.scala
@@ -285,7 +285,7 @@ object GraphGen {
       if (protoPackage.isEmpty) state else state.closeNamespace
     )
 
-  def genRootNode: Gen[RootNode] =
+  def genRootNode: Gen[RootNode] = {
     listWithStatefulGen(State(), maxSize = 10)(genFileNode)
       .map {
         case (files, state) =>
@@ -293,4 +293,6 @@ object GraphGen {
           RootNode(files)
       }
       .suchThat(_.maxMessageId.isDefined)
+
+  }
 }
diff --git a/proptest/src/test/scala/Nodes.scala b/proptest/src/test/scala/Nodes.scala
index 4d47b4b2b..73b0d607e 100644
--- a/proptest/src/test/scala/Nodes.scala
+++ b/proptest/src/test/scala/Nodes.scala
@@ -334,7 +334,8 @@ object Nodes {
           assert(
             fieldOptions.modifier == FieldModifier.OPTIONAL || fieldOptions.modifier == FieldModifier.REPEATED
           )
-          if (fieldOptions.modifier == FieldModifier.OPTIONAL || fieldType.isMap) ""
+          if (fieldOptions.proto3Presence) "optional "
+          else if (fieldOptions.modifier == FieldModifier.OPTIONAL || fieldType.isMap) ""
           else if (fieldOptions.modifier == FieldModifier.REPEATED) "repeated "
           else throw new RuntimeException("Unexpected modifier")
         }
diff --git a/proptest/src/test/scala/SchemaGenerators.scala b/proptest/src/test/scala/SchemaGenerators.scala
index 9dadd3d6d..52420a5c1 100644
--- a/proptest/src/test/scala/SchemaGenerators.scala
+++ b/proptest/src/test/scala/SchemaGenerators.scala
@@ -175,6 +175,7 @@ object SchemaGenerators {
       file.getAbsolutePath
     }
     val args = Seq(
+      "--experimental_allow_proto3_optional",
       "--proto_path",
       (tmpDir.toString + ":protobuf:third_party"),
       "--java_out",