diff --git a/clang-tools-extra/clangd/index/remote/Client.cpp b/clang-tools-extra/clangd/index/remote/Client.cpp
--- a/clang-tools-extra/clangd/index/remote/Client.cpp
+++ b/clang-tools-extra/clangd/index/remote/Client.cpp
@@ -46,8 +46,7 @@
       }
       auto Sym = fromProtobuf(Reply.stream_result(), &Strings);
       if (!Sym)
-        elog("Received invalid {0}: {1}", ReplyT::descriptor()->name(),
-             Reply.stream_result().yaml_serialization());
+        elog("Received invalid {0}", ReplyT::descriptor()->name());
       Callback(*Sym);
     }
     SPAN_ATTACH(Tracer, "status", Reader->Finish().ok());
diff --git a/clang-tools-extra/clangd/index/remote/Index.proto b/clang-tools-extra/clangd/index/remote/Index.proto
--- a/clang-tools-extra/clangd/index/remote/Index.proto
+++ b/clang-tools-extra/clangd/index/remote/Index.proto
@@ -10,6 +10,8 @@
 
 package clang.clangd.remote;
 
+// Semantics of SymbolIndex match clangd::SymbolIndex with all required
+// structures corresponding to their clangd::* counterparts.
 service SymbolIndex {
   rpc Lookup(LookupRequest) returns (stream LookupReply) {}
 
@@ -34,7 +36,7 @@
   repeated string scopes = 2;
   bool any_scope = 3;
   uint32 limit = 4;
-  bool resricted_for_code_completion = 5;
+  bool restricted_for_code_completion = 5;
   repeated string proximity_paths = 6;
   repeated string preferred_types = 7;
 }
@@ -63,7 +65,49 @@
   }
 }
 
-// FIXME(kirillbobyrev): Properly serialize symbols and refs instead of passing
-// YAML.
-message Ref { string yaml_serialization = 1; }
-message Symbol { string yaml_serialization = 1; }
+message Symbol {
+  string id = 1;
+  SymbolInfo info = 2;
+  string name = 3;
+  SymbolLocation definition = 4;
+  string scope = 5;
+  SymbolLocation canonical_declarattion = 6;
+  int32 references = 7;
+  uint32 origin = 8;
+  string signature = 9;
+  string template_specialization_args = 10;
+  string completion_snippet_suffix = 11;
+  string documentation = 12;
+  string return_type = 13;
+  string type = 14;
+  repeated HeaderWithReferences headers = 15;
+  uint32 flags = 16;
+}
+
+message Ref {
+  SymbolLocation location = 1;
+  uint32 kind = 2;
+}
+
+message SymbolInfo {
+  uint32 kind = 1;
+  uint32 subkind = 2;
+  uint32 language = 3;
+  uint32 properties = 4;
+}
+
+message SymbolLocation {
+  Position start = 1;
+  Position end = 2;
+  string file_uri = 3;
+}
+
+message Position {
+  uint32 line = 1;
+  uint32 column = 2;
+}
+
+message HeaderWithReferences {
+  string header = 1;
+  uint32 references = 2;
+}
diff --git a/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.cpp b/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.cpp
--- a/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.cpp
+++ b/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.cpp
@@ -7,13 +7,90 @@
 //===----------------------------------------------------------------------===//
 
 #include "Marshalling.h"
+#include "Index.pb.h"
+#include "Protocol.h"
 #include "index/Serialization.h"
+#include "index/Symbol.h"
+#include "index/SymbolID.h"
+#include "index/SymbolLocation.h"
+#include "index/SymbolOrigin.h"
 #include "support/Logger.h"
+#include "clang/Index/IndexSymbol.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/StringSaver.h"
 
 namespace clang {
 namespace clangd {
 namespace remote {
 
+namespace {
+
+clangd::SymbolLocation::Position fromProtobuf(const Position &Message) {
+  clangd::SymbolLocation::Position Result;
+  Result.setColumn(static_cast<uint32_t>(Message.column()));
+  Result.setLine(static_cast<uint32_t>(Message.line()));
+  return Result;
+}
+
+Position toProtobuf(const clangd::SymbolLocation::Position &Position) {
+  remote::Position Result;
+  Result.set_column(Position.column());
+  Result.set_line(Position.line());
+  return Result;
+}
+
+clang::index::SymbolInfo fromProtobuf(const SymbolInfo &Message) {
+  clang::index::SymbolInfo Result;
+  Result.Kind = static_cast<clang::index::SymbolKind>(Message.kind());
+  Result.SubKind = static_cast<clang::index::SymbolSubKind>(Message.subkind());
+  Result.Lang = static_cast<clang::index::SymbolLanguage>(Message.language());
+  Result.Properties =
+      static_cast<clang::index::SymbolPropertySet>(Message.properties());
+  return Result;
+}
+
+SymbolInfo toProtobuf(const clang::index::SymbolInfo &Info) {
+  SymbolInfo Result;
+  Result.set_kind(static_cast<uint32_t>(Info.Kind));
+  Result.set_subkind(static_cast<uint32_t>(Info.SubKind));
+  Result.set_language(static_cast<uint32_t>(Info.Lang));
+  Result.set_properties(static_cast<uint32_t>(Info.Properties));
+  return Result;
+}
+
+clangd::SymbolLocation fromProtobuf(const SymbolLocation &Message,
+                                    llvm::UniqueStringSaver *Strings) {
+  clangd::SymbolLocation Location;
+  Location.Start = fromProtobuf(Message.start());
+  Location.End = fromProtobuf(Message.end());
+  Location.FileURI = Strings->save(Message.file_uri()).begin();
+  return Location;
+}
+
+SymbolLocation toProtobuf(const clangd::SymbolLocation &Location) {
+  remote::SymbolLocation Result;
+  *Result.mutable_start() = toProtobuf(Location.Start);
+  *Result.mutable_end() = toProtobuf(Location.End);
+  *Result.mutable_file_uri() = Location.FileURI;
+  return Result;
+}
+
+HeaderWithReferences
+toProtobuf(const clangd::Symbol::IncludeHeaderWithReferences &IncludeHeader) {
+  HeaderWithReferences Result;
+  Result.set_header(IncludeHeader.IncludeHeader.str());
+  Result.set_references(IncludeHeader.References);
+  return Result;
+}
+
+clangd::Symbol::IncludeHeaderWithReferences
+fromProtobuf(const HeaderWithReferences &Message) {
+  return clangd::Symbol::IncludeHeaderWithReferences{Message.header(),
+                                                     Message.references()};
+}
+
+} // namespace
+
 clangd::FuzzyFindRequest fromProtobuf(const FuzzyFindRequest *Request) {
   clangd::FuzzyFindRequest Result;
   Result.Query = Request->query();
@@ -22,7 +99,7 @@
   Result.AnyScope = Request->any_scope();
   if (Request->limit())
     Result.Limit = Request->limit();
-  Result.RestrictForCodeCompletion = Request->resricted_for_code_completion();
+  Result.RestrictForCodeCompletion = Request->restricted_for_code_completion();
   for (const auto &Path : Request->proximity_paths())
     Result.ProximityPaths.push_back(Path);
   for (const auto &Type : Request->preferred_types())
@@ -32,21 +109,50 @@
 
 llvm::Optional<clangd::Symbol> fromProtobuf(const Symbol &Message,
                                             llvm::UniqueStringSaver *Strings) {
-  auto Result = symbolFromYAML(Message.yaml_serialization(), Strings);
-  if (!Result) {
-    elog("Cannot convert Symbol from Protobuf: {}", Result.takeError());
+  if (!Message.has_info() || !Message.has_definition() ||
+      !Message.has_canonical_declarattion()) {
+    elog("Cannot convert Symbol from Protobuf: {}", Message.ShortDebugString());
     return llvm::None;
   }
-  return *Result;
+  clangd::Symbol Result;
+  auto ID = SymbolID::fromStr(Message.id());
+  if (!ID) {
+    elog("Cannot convert parse SymbolID {} from Protobuf: {}", ID.takeError(),
+         Message.ShortDebugString());
+    return llvm::None;
+  }
+  Result.ID = *ID;
+  Result.SymInfo = fromProtobuf(Message.info());
+  Result.Name = Message.name();
+  Result.Scope = Message.scope();
+  Result.Definition = fromProtobuf(Message.definition(), Strings);
+  Result.CanonicalDeclaration =
+      fromProtobuf(Message.canonical_declarattion(), Strings);
+  Result.References = Message.references();
+  Result.Origin = static_cast<clangd::SymbolOrigin>(Message.origin());
+  Result.Signature = Message.signature();
+  Result.TemplateSpecializationArgs = Message.template_specialization_args();
+  Result.CompletionSnippetSuffix = Message.completion_snippet_suffix();
+  Result.Documentation = Message.documentation();
+  Result.ReturnType = Message.return_type();
+  Result.Type = Message.type();
+  for (const auto &Header : Message.headers()) {
+    Result.IncludeHeaders.push_back(fromProtobuf(Header));
+  }
+  Result.Flags = static_cast<clangd::Symbol::SymbolFlag>(Message.flags());
+  return Result;
 }
+
 llvm::Optional<clangd::Ref> fromProtobuf(const Ref &Message,
                                          llvm::UniqueStringSaver *Strings) {
-  auto Result = refFromYAML(Message.yaml_serialization(), Strings);
-  if (!Result) {
-    elog("Cannot convert Ref from Protobuf: {}", Result.takeError());
+  if (!Message.has_location()) {
+    elog("Cannot convert Ref from Protobuf: {}", Message.ShortDebugString());
     return llvm::None;
   }
-  return *Result;
+  clangd::Ref Result;
+  Result.Location = fromProtobuf(Message.location(), Strings);
+  Result.Kind = static_cast<clangd::RefKind>(Message.kind());
+  return Result;
 }
 
 LookupRequest toProtobuf(const clangd::LookupRequest &From) {
@@ -64,7 +170,7 @@
   RPCRequest.set_any_scope(From.AnyScope);
   if (From.Limit)
     RPCRequest.set_limit(*From.Limit);
-  RPCRequest.set_resricted_for_code_completion(From.RestrictForCodeCompletion);
+  RPCRequest.set_restricted_for_code_completion(From.RestrictForCodeCompletion);
   for (const auto &Path : From.ProximityPaths)
     RPCRequest.add_proximity_paths(Path);
   for (const auto &Type : From.PreferredTypes)
@@ -84,13 +190,34 @@
 
 Symbol toProtobuf(const clangd::Symbol &From) {
   Symbol Result;
-  Result.set_yaml_serialization(toYAML(From));
+  Result.set_id(From.ID.str());
+  *Result.mutable_info() = toProtobuf(From.SymInfo);
+  Result.set_name(From.Name.str());
+  *Result.mutable_definition() = toProtobuf(From.Definition);
+  Result.set_scope(From.Scope.str());
+  *Result.mutable_canonical_declarattion() =
+      toProtobuf(From.CanonicalDeclaration);
+  Result.set_references(From.References);
+  Result.set_origin(static_cast<uint32_t>(From.Origin));
+  Result.set_signature(From.Signature.str());
+  Result.set_template_specialization_args(
+      From.TemplateSpecializationArgs.str());
+  Result.set_completion_snippet_suffix(From.CompletionSnippetSuffix.str());
+  Result.set_documentation(From.Documentation.str());
+  Result.set_return_type(From.ReturnType.str());
+  Result.set_type(From.Type.str());
+  for (const auto &Header : From.IncludeHeaders) {
+    auto *NextHeader = Result.add_headers();
+    *NextHeader = toProtobuf(Header);
+  }
+  Result.set_flags(static_cast<uint32_t>(From.Flags));
   return Result;
 }
 
 Ref toProtobuf(const clangd::Ref &From) {
   Ref Result;
-  Result.set_yaml_serialization(toYAML(From));
+  Result.set_kind(static_cast<uint32_t>(From.Kind));
+  *Result.mutable_location() = toProtobuf(From.Location);
   return Result;
 }
 
diff --git a/clang-tools-extra/clangd/unittests/CMakeLists.txt b/clang-tools-extra/clangd/unittests/CMakeLists.txt
--- a/clang-tools-extra/clangd/unittests/CMakeLists.txt
+++ b/clang-tools-extra/clangd/unittests/CMakeLists.txt
@@ -120,6 +120,10 @@
   add_subdirectory(xpc)
 endif ()
 
+if (CLANGD_ENABLE_REMOTE)
+  add_subdirectory(remote)
+endif()
+
 configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.py.in
   ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg.py)
diff --git a/clang-tools-extra/clangd/unittests/TestTU.h b/clang-tools-extra/clangd/unittests/TestTU.h
--- a/clang-tools-extra/clangd/unittests/TestTU.h
+++ b/clang-tools-extra/clangd/unittests/TestTU.h
@@ -70,6 +70,11 @@
   ParsedAST build() const;
   ParseInputs inputs() const;
   SymbolSlab headerSymbols() const;
+  RefSlab headerRefs() const;
+  // Returns all symbols from the header and main file.
+  SymbolSlab symbols() const;
+  // Returns all references from the header and main file.
+  RefSlab refs() const;
   std::unique_ptr<SymbolIndex> index() const;
 };
 
diff --git a/clang-tools-extra/clangd/unittests/TestTU.cpp b/clang-tools-extra/clangd/unittests/TestTU.cpp
--- a/clang-tools-extra/clangd/unittests/TestTU.cpp
+++ b/clang-tools-extra/clangd/unittests/TestTU.cpp
@@ -113,6 +113,39 @@
                                         AST.getCanonicalIncludes()));
 }
 
+RefSlab TestTU::headerRefs() const {
+  auto AST = build();
+  return std::get<1>(indexHeaderSymbols(/*Version=*/"null", AST.getASTContext(),
+                                        AST.getPreprocessorPtr(),
+                                        AST.getCanonicalIncludes()));
+}
+
+SymbolSlab TestTU::symbols() const {
+  auto AST = build();
+  const auto MainCodeSymbols = std::get<0>(indexMainDecls(AST));
+  const auto HeaderSymbols = headerSymbols();
+  SymbolSlab::Builder Merger;
+  for (const auto &Sym : MainCodeSymbols)
+    Merger.insert(Sym);
+  for (const auto &Sym : HeaderSymbols)
+    Merger.insert(Sym);
+  return std::move(Merger).build();
+}
+
+RefSlab TestTU::refs() const {
+  auto AST = build();
+  const auto MainCodeRefs = std::get<1>(indexMainDecls(AST));
+  const auto HeaderRefs = headerRefs();
+  RefSlab::Builder Merger;
+  for (const auto &SymbolReferences : MainCodeRefs)
+    for (const auto &Reference : SymbolReferences.second)
+      Merger.insert(SymbolReferences.first, Reference);
+  for (const auto &SymbolReferences : HeaderRefs)
+    for (const auto &Reference : SymbolReferences.second)
+      Merger.insert(SymbolReferences.first, Reference);
+  return std::move(Merger).build();
+}
+
 std::unique_ptr<SymbolIndex> TestTU::index() const {
   auto AST = build();
   auto Idx = std::make_unique<FileIndex>(/*UseDex=*/true);
diff --git a/clang-tools-extra/clangd/unittests/remote/CMakeLists.txt b/clang-tools-extra/clangd/unittests/remote/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/clangd/unittests/remote/CMakeLists.txt
@@ -0,0 +1,26 @@
+set(LLVM_LINK_COMPONENTS
+  Support
+  )
+
+get_filename_component(CLANGD_SOURCE_DIR
+  ${CMAKE_CURRENT_SOURCE_DIR}/../../clangd REALPATH)
+include_directories(
+  ${CLANGD_SOURCE_DIR}
+  )
+
+include_directories(${CMAKE_CURRENT_BINARY_DIR}/../../index/remote)
+add_definitions(-DGOOGLE_PROTOBUF_NO_RTTI=1)
+
+add_custom_target(ClangdRemoteUnitTests)
+add_unittest(ClangdRemoteUnitTests ClangdRemoteTests
+  MarshallingTests.cpp
+
+  ../TestTU.cpp
+  ../TestFS.cpp
+  )
+
+target_link_libraries(ClangdRemoteTests
+  PRIVATE
+  clangDaemon
+  clangdRemoteMarshalling
+  )
diff --git a/clang-tools-extra/clangd/unittests/remote/MarshallingTests.cpp b/clang-tools-extra/clangd/unittests/remote/MarshallingTests.cpp
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/clangd/unittests/remote/MarshallingTests.cpp
@@ -0,0 +1,87 @@
+//===--- MarshallingTests.cpp ------------------------------------*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "../TestTU.h"
+#include "index/Serialization.h"
+#include "index/remote/marshalling/Marshalling.h"
+#include "llvm/Support/StringSaver.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace clangd {
+namespace remote {
+namespace {
+
+class RemoteMarshallingTest : public ::testing::Test {
+public:
+  RemoteMarshallingTest() : Strings(NewArena) {
+    TU.HeaderCode = R"(
+    // This is a class.
+    class Foo {
+    public:
+      Foo();
+
+      int Bar;
+    private:
+      double Number;
+    };
+    /// This is a function.
+    char baz();
+    template <typename T>
+    T getT ();
+    struct FooBar {};
+    )";
+    TU.Code = R"(
+    const int GlobalVariable = 123;
+
+    class ForwardDecl;
+    char baz() { return 'x'; }
+    template <typename T>
+    T getT() { return T(); }
+    Foo::Foo() : Bar(GlobalVariable), Number(42) {
+      for (int Counter = 0; Counter < GlobalVariable; ++Counter) {
+        baz();
+        getT<FooBar>();
+      }
+    }
+    )";
+  }
+
+  SymbolSlab symbols() { return TU.symbols(); }
+  RefSlab refs() { return TU.refs(); }
+
+  llvm::UniqueStringSaver Strings;
+
+private:
+  TestTU TU;
+  llvm::BumpPtrAllocator NewArena;
+};
+
+TEST_F(RemoteMarshallingTest, SymbolSerialization) {
+  for (auto &Sym : symbols()) {
+    const auto ProtobufMeessage = toProtobuf(Sym);
+    const auto SymToProtobufAndBack = fromProtobuf(ProtobufMeessage, &Strings);
+    EXPECT_TRUE(SymToProtobufAndBack.hasValue());
+    EXPECT_EQ(toYAML(Sym), toYAML(*SymToProtobufAndBack));
+  }
+}
+
+TEST_F(RemoteMarshallingTest, ReferenceSerialization) {
+  for (const auto &SymbolWithRefs : refs()) {
+    for (const auto &Ref : SymbolWithRefs.second) {
+      const auto RefToProtobufAndBack = fromProtobuf(toProtobuf(Ref), &Strings);
+      EXPECT_TRUE(RefToProtobufAndBack.hasValue());
+      EXPECT_EQ(toYAML(Ref), toYAML(*RefToProtobufAndBack));
+    }
+  }
+}
+
+} // namespace
+} // namespace remote
+} // namespace clangd
+} // namespace clang