diff --git a/csharp/.gitignore b/csharp/.gitignore
index 62c96383ce..56ac1494d6 100644
--- a/csharp/.gitignore
+++ b/csharp/.gitignore
@@ -33,3 +33,8 @@ lib/protoc.exe
 
 # Benchmark output
 BenchmarkDotNet.Artifacts/
+
+# Reinstate generated code for test files
+!any_test.pb.*
+!map*unittest.pb.*
+!unittest*.pb.*
diff --git a/csharp/BUILD.bazel b/csharp/BUILD.bazel
index 9f9e83a511..23fbe411f9 100644
--- a/csharp/BUILD.bazel
+++ b/csharp/BUILD.bazel
@@ -45,17 +45,17 @@ filegroup(
 filegroup(
     name = "wkt_cs_srcs",
     srcs = [
-        "src/Google.Protobuf/Reflection/Descriptor.cs",
-        "src/Google.Protobuf/WellKnownTypes/Any.cs",
-        "src/Google.Protobuf/WellKnownTypes/Api.cs",
-        "src/Google.Protobuf/WellKnownTypes/Duration.cs",
-        "src/Google.Protobuf/WellKnownTypes/Empty.cs",
-        "src/Google.Protobuf/WellKnownTypes/FieldMask.cs",
-        "src/Google.Protobuf/WellKnownTypes/SourceContext.cs",
-        "src/Google.Protobuf/WellKnownTypes/Struct.cs",
-        "src/Google.Protobuf/WellKnownTypes/Timestamp.cs",
-        "src/Google.Protobuf/WellKnownTypes/Type.cs",
-        "src/Google.Protobuf/WellKnownTypes/Wrappers.cs",
+        "src/Google.Protobuf/Reflection/Descriptor.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/Any.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/Api.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/Duration.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/Empty.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/FieldMask.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/SourceContext.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/Struct.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/Timestamp.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/Type.pb.cs",
+        "src/Google.Protobuf/WellKnownTypes/Wrappers.pb.cs",
     ],
     visibility = ["//src/google/protobuf/compiler/csharp:__pkg__"],
 )
diff --git a/csharp/generate_protos.sh b/csharp/generate_protos.sh
index cfd6082708..8be4428405 100755
--- a/csharp/generate_protos.sh
+++ b/csharp/generate_protos.sh
@@ -32,6 +32,7 @@ fi
 # descriptor.proto and well-known types
 $PROTOC -Isrc --csharp_out=csharp/src/Google.Protobuf \
     --csharp_opt=base_namespace=Google.Protobuf \
+    --csharp_opt=file_extension=.pb.cs \
     src/google/protobuf/descriptor.proto \
     src/google/protobuf/any.proto \
     src/google/protobuf/api.proto \
@@ -52,6 +53,7 @@ $PROTOC -Isrc --csharp_out=csharp/src/Google.Protobuf \
 $PROTOC -Isrc -Icsharp/protos \
     --experimental_allow_proto3_optional \
     --csharp_out=csharp/src/Google.Protobuf.Test.TestProtos \
+    --csharp_opt=file_extension=.pb.cs \
     --descriptor_set_out=csharp/src/Google.Protobuf.Test/testprotos.pb \
     --include_source_info \
     --include_imports \
@@ -75,4 +77,5 @@ $PROTOC -Isrc -Icsharp/protos \
 
 # AddressBook sample protos
 $PROTOC -Iexamples -Isrc --csharp_out=csharp/src/AddressBook \
+    --csharp_opt=file_extension=.pb.cs \
     examples/addressbook.proto
diff --git a/csharp/src/AddressBook/Addressbook.cs b/csharp/src/AddressBook/Addressbook.pb.cs
similarity index 100%
rename from csharp/src/AddressBook/Addressbook.cs
rename to csharp/src/AddressBook/Addressbook.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/MapUnittestProto3.cs b/csharp/src/Google.Protobuf.Test.TestProtos/MapUnittestProto3.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/MapUnittestProto3.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/MapUnittestProto3.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/TestMessagesProto2.cs b/csharp/src/Google.Protobuf.Test.TestProtos/TestMessagesProto2.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/TestMessagesProto2.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/TestMessagesProto2.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/TestMessagesProto3.cs b/csharp/src/Google.Protobuf.Test.TestProtos/TestMessagesProto3.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/TestMessagesProto3.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/TestMessagesProto3.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/Unittest.cs b/csharp/src/Google.Protobuf.Test.TestProtos/Unittest.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/Unittest.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/Unittest.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestCustomOptionsProto3.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestCustomOptionsProto3.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestCustomOptionsProto3.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestCustomOptionsProto3.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImport.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImport.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestImport.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestImport.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportProto3.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportProto3.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportProto3.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportProto3.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublic.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublic.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublic.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublic.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublicProto3.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublicProto3.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublicProto3.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestImportPublicProto3.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936A.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936A.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936A.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936A.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936B.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936B.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936B.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936B.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936C.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936C.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936C.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssue6936C.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssues.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssues.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssues.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestIssues.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestProto3.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestProto3.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestProto3.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestProto3.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestProto3Optional.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestProto3Optional.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestProto3Optional.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestProto3Optional.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestSelfreferentialOptions.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestSelfreferentialOptions.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestSelfreferentialOptions.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestSelfreferentialOptions.pb.cs
diff --git a/csharp/src/Google.Protobuf.Test.TestProtos/UnittestWellKnownTypes.cs b/csharp/src/Google.Protobuf.Test.TestProtos/UnittestWellKnownTypes.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf.Test.TestProtos/UnittestWellKnownTypes.cs
rename to csharp/src/Google.Protobuf.Test.TestProtos/UnittestWellKnownTypes.pb.cs
diff --git a/csharp/src/Google.Protobuf/Compiler/Plugin.cs b/csharp/src/Google.Protobuf/Compiler/Plugin.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/Compiler/Plugin.cs
rename to csharp/src/Google.Protobuf/Compiler/Plugin.pb.cs
diff --git a/csharp/src/Google.Protobuf/Reflection/Descriptor.cs b/csharp/src/Google.Protobuf/Reflection/Descriptor.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/Reflection/Descriptor.cs
rename to csharp/src/Google.Protobuf/Reflection/Descriptor.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Any.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/Any.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Api.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/Api.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Duration.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/Duration.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Empty.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/Empty.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs b/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Struct.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/Struct.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Type.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/Type.pb.cs
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.pb.cs
similarity index 100%
rename from csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
rename to csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.pb.cs