diff --git a/gitaly.proto b/gitaly.proto
index 34159704815f5d558e2316e3b4b318ccf7aee9fc..2677486240fa1cf82e89c502ac15e8e8d37d2cbe 100644
--- a/gitaly.proto
+++ b/gitaly.proto
@@ -15,6 +15,11 @@ service Notifications {
   rpc PostReceive(PostReceiveRequest) returns (PostReceiveResponse) {}
 }
 
+service Diff {
+ // Returns stream of CommitDiffResponse: 1 per changed file
+  rpc CommitDiff(CommitDiffRequest) returns (stream CommitDiffResponse) {};
+}
+
 message InfoRefsRequest {
   Repository repository = 1;
 }
@@ -32,3 +37,22 @@ message PostReceiveRequest {
 }
 
 message PostReceiveResponse {}
+
+message CommitDiffRequest {
+  Repository repository = 1;
+  string left_commit_id = 2;
+  string right_commit_id = 3;
+}
+
+// A CommitDiffResponse corresponds to a single changed file in a commit.
+message CommitDiffResponse {
+  bytes from_path = 1;
+  bytes to_path = 2;
+  // Blob ID as returned via `git diff --full-index`
+  string from_id = 3;
+  string to_id = 4;
+  int32 old_mode = 5;
+  int32 new_mode = 6;
+  bool binary = 7;
+  repeated bytes raw_chunks = 8;
+}
diff --git a/go/gitaly.pb.go b/go/gitaly.pb.go
index 1ccf60c6c3cdc21da04f98e4c088123eac79e485..2f50e60bb7fa4499ce46cf6650528d42c185e128 100644
--- a/go/gitaly.pb.go
+++ b/go/gitaly.pb.go
@@ -14,6 +14,8 @@ It has these top-level messages:
 	Repository
 	PostReceiveRequest
 	PostReceiveResponse
+	CommitDiffRequest
+	CommitDiffResponse
 */
 package gitaly
 
@@ -109,12 +111,120 @@ func (m *PostReceiveResponse) String() string            { return proto.CompactT
 func (*PostReceiveResponse) ProtoMessage()               {}
 func (*PostReceiveResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{4} }
 
+type CommitDiffRequest struct {
+	Repository    *Repository `protobuf:"bytes,1,opt,name=repository" json:"repository,omitempty"`
+	LeftCommitId  string      `protobuf:"bytes,2,opt,name=left_commit_id,json=leftCommitId" json:"left_commit_id,omitempty"`
+	RightCommitId string      `protobuf:"bytes,3,opt,name=right_commit_id,json=rightCommitId" json:"right_commit_id,omitempty"`
+}
+
+func (m *CommitDiffRequest) Reset()                    { *m = CommitDiffRequest{} }
+func (m *CommitDiffRequest) String() string            { return proto.CompactTextString(m) }
+func (*CommitDiffRequest) ProtoMessage()               {}
+func (*CommitDiffRequest) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{5} }
+
+func (m *CommitDiffRequest) GetRepository() *Repository {
+	if m != nil {
+		return m.Repository
+	}
+	return nil
+}
+
+func (m *CommitDiffRequest) GetLeftCommitId() string {
+	if m != nil {
+		return m.LeftCommitId
+	}
+	return ""
+}
+
+func (m *CommitDiffRequest) GetRightCommitId() string {
+	if m != nil {
+		return m.RightCommitId
+	}
+	return ""
+}
+
+// A CommitDiffResponse corresponds to a single changed file in a commit.
+type CommitDiffResponse struct {
+	FromPath []byte `protobuf:"bytes,1,opt,name=from_path,json=fromPath,proto3" json:"from_path,omitempty"`
+	ToPath   []byte `protobuf:"bytes,2,opt,name=to_path,json=toPath,proto3" json:"to_path,omitempty"`
+	// Blob ID as returned via `git diff --full-index`
+	FromId    string   `protobuf:"bytes,3,opt,name=from_id,json=fromId" json:"from_id,omitempty"`
+	ToId      string   `protobuf:"bytes,4,opt,name=to_id,json=toId" json:"to_id,omitempty"`
+	OldMode   int32    `protobuf:"varint,5,opt,name=old_mode,json=oldMode" json:"old_mode,omitempty"`
+	NewMode   int32    `protobuf:"varint,6,opt,name=new_mode,json=newMode" json:"new_mode,omitempty"`
+	Binary    bool     `protobuf:"varint,7,opt,name=binary" json:"binary,omitempty"`
+	RawChunks [][]byte `protobuf:"bytes,8,rep,name=raw_chunks,json=rawChunks,proto3" json:"raw_chunks,omitempty"`
+}
+
+func (m *CommitDiffResponse) Reset()                    { *m = CommitDiffResponse{} }
+func (m *CommitDiffResponse) String() string            { return proto.CompactTextString(m) }
+func (*CommitDiffResponse) ProtoMessage()               {}
+func (*CommitDiffResponse) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{6} }
+
+func (m *CommitDiffResponse) GetFromPath() []byte {
+	if m != nil {
+		return m.FromPath
+	}
+	return nil
+}
+
+func (m *CommitDiffResponse) GetToPath() []byte {
+	if m != nil {
+		return m.ToPath
+	}
+	return nil
+}
+
+func (m *CommitDiffResponse) GetFromId() string {
+	if m != nil {
+		return m.FromId
+	}
+	return ""
+}
+
+func (m *CommitDiffResponse) GetToId() string {
+	if m != nil {
+		return m.ToId
+	}
+	return ""
+}
+
+func (m *CommitDiffResponse) GetOldMode() int32 {
+	if m != nil {
+		return m.OldMode
+	}
+	return 0
+}
+
+func (m *CommitDiffResponse) GetNewMode() int32 {
+	if m != nil {
+		return m.NewMode
+	}
+	return 0
+}
+
+func (m *CommitDiffResponse) GetBinary() bool {
+	if m != nil {
+		return m.Binary
+	}
+	return false
+}
+
+func (m *CommitDiffResponse) GetRawChunks() [][]byte {
+	if m != nil {
+		return m.RawChunks
+	}
+	return nil
+}
+
 func init() {
 	proto.RegisterType((*InfoRefsRequest)(nil), "gitaly.InfoRefsRequest")
 	proto.RegisterType((*InfoRefsResponse)(nil), "gitaly.InfoRefsResponse")
 	proto.RegisterType((*Repository)(nil), "gitaly.Repository")
 	proto.RegisterType((*PostReceiveRequest)(nil), "gitaly.PostReceiveRequest")
 	proto.RegisterType((*PostReceiveResponse)(nil), "gitaly.PostReceiveResponse")
+	proto.RegisterType((*CommitDiffRequest)(nil), "gitaly.CommitDiffRequest")
+	proto.RegisterType((*CommitDiffResponse)(nil), "gitaly.CommitDiffResponse")
 }
 
 // Reference imports to suppress errors if they are not otherwise used.
@@ -344,24 +454,130 @@ var _Notifications_serviceDesc = grpc.ServiceDesc{
 	Metadata: "gitaly.proto",
 }
 
+// Client API for Diff service
+
+type DiffClient interface {
+	// Returns stream of CommitDiffResponse: 1 per changed file
+	CommitDiff(ctx context.Context, in *CommitDiffRequest, opts ...grpc.CallOption) (Diff_CommitDiffClient, error)
+}
+
+type diffClient struct {
+	cc *grpc.ClientConn
+}
+
+func NewDiffClient(cc *grpc.ClientConn) DiffClient {
+	return &diffClient{cc}
+}
+
+func (c *diffClient) CommitDiff(ctx context.Context, in *CommitDiffRequest, opts ...grpc.CallOption) (Diff_CommitDiffClient, error) {
+	stream, err := grpc.NewClientStream(ctx, &_Diff_serviceDesc.Streams[0], c.cc, "/gitaly.Diff/CommitDiff", opts...)
+	if err != nil {
+		return nil, err
+	}
+	x := &diffCommitDiffClient{stream}
+	if err := x.ClientStream.SendMsg(in); err != nil {
+		return nil, err
+	}
+	if err := x.ClientStream.CloseSend(); err != nil {
+		return nil, err
+	}
+	return x, nil
+}
+
+type Diff_CommitDiffClient interface {
+	Recv() (*CommitDiffResponse, error)
+	grpc.ClientStream
+}
+
+type diffCommitDiffClient struct {
+	grpc.ClientStream
+}
+
+func (x *diffCommitDiffClient) Recv() (*CommitDiffResponse, error) {
+	m := new(CommitDiffResponse)
+	if err := x.ClientStream.RecvMsg(m); err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
+// Server API for Diff service
+
+type DiffServer interface {
+	// Returns stream of CommitDiffResponse: 1 per changed file
+	CommitDiff(*CommitDiffRequest, Diff_CommitDiffServer) error
+}
+
+func RegisterDiffServer(s *grpc.Server, srv DiffServer) {
+	s.RegisterService(&_Diff_serviceDesc, srv)
+}
+
+func _Diff_CommitDiff_Handler(srv interface{}, stream grpc.ServerStream) error {
+	m := new(CommitDiffRequest)
+	if err := stream.RecvMsg(m); err != nil {
+		return err
+	}
+	return srv.(DiffServer).CommitDiff(m, &diffCommitDiffServer{stream})
+}
+
+type Diff_CommitDiffServer interface {
+	Send(*CommitDiffResponse) error
+	grpc.ServerStream
+}
+
+type diffCommitDiffServer struct {
+	grpc.ServerStream
+}
+
+func (x *diffCommitDiffServer) Send(m *CommitDiffResponse) error {
+	return x.ServerStream.SendMsg(m)
+}
+
+var _Diff_serviceDesc = grpc.ServiceDesc{
+	ServiceName: "gitaly.Diff",
+	HandlerType: (*DiffServer)(nil),
+	Methods:     []grpc.MethodDesc{},
+	Streams: []grpc.StreamDesc{
+		{
+			StreamName:    "CommitDiff",
+			Handler:       _Diff_CommitDiff_Handler,
+			ServerStreams: true,
+		},
+	},
+	Metadata: "gitaly.proto",
+}
+
 func init() { proto.RegisterFile("gitaly.proto", fileDescriptor0) }
 
 var fileDescriptor0 = []byte{
-	// 256 bytes of a gzipped FileDescriptorProto
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+	// 463 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88, 0x02, 0xff, 0xa4, 0x53, 0x5d, 0x6e, 0xd3, 0x40,
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+	0xf0, 0x35, 0x3c, 0x4d, 0x65, 0xa2, 0xa3, 0xd8, 0xb8, 0x45, 0x4a, 0xb8, 0x07, 0xe6, 0x43, 0x9c,
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+	0x36, 0x70, 0xab, 0x0b, 0xfe, 0x5a, 0x80, 0xdb, 0x7d, 0xad, 0xa7, 0x78, 0x0e, 0xa3, 0xa4, 0xa4,
+	0x2c, 0xda, 0x0c, 0xca, 0x61, 0xc3, 0x1a, 0x98, 0x73, 0xbd, 0xc0, 0x53, 0x18, 0x68, 0x6a, 0xa8,
+	0x03, 0x43, 0xd9, 0x9a, 0x5a, 0xc2, 0x64, 0x6d, 0x8a, 0xd9, 0x75, 0x38, 0x13, 0x38, 0x86, 0xbe,
+	0xa6, 0x1a, 0xee, 0x35, 0x33, 0xd7, 0x34, 0x13, 0x78, 0x06, 0x43, 0x4a, 0x45, 0x94, 0x91, 0x90,
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+	0xb2, 0x1b, 0x2a, 0x97, 0x4b, 0x43, 0xbd, 0x04, 0xfb, 0x46, 0xe5, 0xbc, 0x5c, 0xb9, 0x03, 0xdf,
+	0x9a, 0x0c, 0xd9, 0x3a, 0xc2, 0x57, 0x00, 0x25, 0x5f, 0x46, 0xf1, 0xe2, 0x3e, 0xbf, 0xab, 0xdc,
+	0xa1, 0x7f, 0x38, 0x71, 0xd8, 0xa8, 0xe4, 0xcb, 0x2b, 0x03, 0x84, 0x7f, 0x2c, 0x18, 0x7d, 0xcb,
+	0x78, 0xa9, 0xa7, 0xd7, 0xd7, 0x73, 0xfc, 0x08, 0xd8, 0x1e, 0xce, 0xf7, 0x22, 0x25, 0x2e, 0xe6,
+	0x3c, 0xbe, 0xc3, 0xd3, 0x76, 0xf2, 0x0f, 0x6e, 0xd3, 0x73, 0x77, 0x89, 0xf5, 0x5a, 0x9f, 0xbc,
+	0xb1, 0xf0, 0x13, 0x8c, 0x3b, 0xdc, 0x6c, 0x7d, 0x0f, 0xb7, 0xf0, 0x07, 0x1c, 0x7f, 0x21, 0xad,
+	0x12, 0x15, 0x73, 0xad, 0x28, 0xaf, 0x70, 0x0a, 0x47, 0x5b, 0x07, 0x85, 0x5e, 0x9b, 0xbd, 0x7b,
+	0xaf, 0xde, 0xf9, 0xa3, 0x5c, 0x6b, 0x1e, 0x7e, 0x85, 0x5e, 0xbd, 0x64, 0xfc, 0x00, 0xd0, 0xad,
+	0x1c, 0xcf, 0xda, 0xa4, 0x9d, 0xf3, 0xf4, 0xbc, 0xc7, 0xa8, 0xae, 0xd7, 0x1b, 0xdb, 0xfc, 0xd5,
+	0x6f, 0xff, 0x05, 0x00, 0x00, 0xff, 0xff, 0x12, 0xbc, 0x0a, 0xd3, 0xe5, 0x03, 0x00, 0x00,
 }
diff --git a/ruby/lib/gitaly/gitaly_pb.rb b/ruby/lib/gitaly/gitaly_pb.rb
index 9a040343e7c37ba9b3261b348d4cc61684f54cfc..f92dc5443a3fb57b53d0d858ab0080f829df968d 100644
--- a/ruby/lib/gitaly/gitaly_pb.rb
+++ b/ruby/lib/gitaly/gitaly_pb.rb
@@ -18,6 +18,21 @@ Google::Protobuf::DescriptorPool.generated_pool.build do
   end
   add_message "gitaly.PostReceiveResponse" do
   end
+  add_message "gitaly.CommitDiffRequest" do
+    optional :repository, :message, 1, "gitaly.Repository"
+    optional :left_commit_id, :string, 2
+    optional :right_commit_id, :string, 3
+  end
+  add_message "gitaly.CommitDiffResponse" do
+    optional :from_path, :bytes, 1
+    optional :to_path, :bytes, 2
+    optional :from_id, :string, 3
+    optional :to_id, :string, 4
+    optional :old_mode, :int32, 5
+    optional :new_mode, :int32, 6
+    optional :binary, :bool, 7
+    repeated :raw_chunks, :bytes, 8
+  end
 end
 
 module Gitaly
@@ -26,4 +41,6 @@ module Gitaly
   Repository = Google::Protobuf::DescriptorPool.generated_pool.lookup("gitaly.Repository").msgclass
   PostReceiveRequest = Google::Protobuf::DescriptorPool.generated_pool.lookup("gitaly.PostReceiveRequest").msgclass
   PostReceiveResponse = Google::Protobuf::DescriptorPool.generated_pool.lookup("gitaly.PostReceiveResponse").msgclass
+  CommitDiffRequest = Google::Protobuf::DescriptorPool.generated_pool.lookup("gitaly.CommitDiffRequest").msgclass
+  CommitDiffResponse = Google::Protobuf::DescriptorPool.generated_pool.lookup("gitaly.CommitDiffResponse").msgclass
 end
diff --git a/ruby/lib/gitaly/gitaly_services_pb.rb b/ruby/lib/gitaly/gitaly_services_pb.rb
index 52872cd371fb22347d8f453146b227728d88d70b..b11fe0b1c54e9faae65372a50d667af4bbe0c619 100644
--- a/ruby/lib/gitaly/gitaly_services_pb.rb
+++ b/ruby/lib/gitaly/gitaly_services_pb.rb
@@ -35,6 +35,21 @@ module Gitaly
       rpc :PostReceive, PostReceiveRequest, PostReceiveResponse
     end
 
+    Stub = Service.rpc_stub_class
+  end
+  module Diff
+    class Service
+
+      include GRPC::GenericService
+
+      self.marshal_class_method = :encode
+      self.unmarshal_class_method = :decode
+      self.service_name = 'gitaly.Diff'
+
+      # Returns stream of CommitDiffResponse: 1 per changed file
+      rpc :CommitDiff, CommitDiffRequest, stream(CommitDiffResponse)
+    end
+
     Stub = Service.rpc_stub_class
   end
 end