diff --git a/clang-tools-extra/clangd/ConfigFragment.h b/clang-tools-extra/clangd/ConfigFragment.h
--- a/clang-tools-extra/clangd/ConfigFragment.h
+++ b/clang-tools-extra/clangd/ConfigFragment.h
@@ -162,6 +162,23 @@
     /// This is checked for translation units only, not headers they include.
     /// Legal values are "Build" or "Skip".
     llvm::Optional<Located<std::string>> Background;
+    /// Configuration information for an external index. If both File and Server
+    /// are set, Server will be ignored. This will be used by index
+    /// implementations to distribute queries to different index sources based
+    /// on the file.
+    struct ExternalBlock {
+      /// Path to a monolithic index on disk. Absolute in case of a global
+      /// config, relative to location the config file containing the fragment
+      /// otherwise.
+      llvm::Optional<Located<std::string>> File;
+      /// Address and port number for a remote-index. e.g. `123.1.1.1:13337`.
+      llvm::Optional<Located<std::string>> Server;
+      /// Source root governed by this index. None implies current config file
+      /// location. Absolute in case of user config and relative otherwise.
+      /// Should always use forward-slashes.
+      llvm::Optional<Located<std::string>> MountPoint;
+    };
+    llvm::Optional<ExternalBlock> External;
   };
   IndexBlock Index;
 
diff --git a/clang-tools-extra/clangd/ConfigYAML.cpp b/clang-tools-extra/clangd/ConfigYAML.cpp
--- a/clang-tools-extra/clangd/ConfigYAML.cpp
+++ b/clang-tools-extra/clangd/ConfigYAML.cpp
@@ -5,8 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-
 #include "ConfigFragment.h"
+#include "Features.inc"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/StringRef.h"
@@ -86,6 +86,25 @@
     DictParser Dict("Index", this);
     Dict.handle("Background",
                 [&](Node &N) { F.Background = scalarValue(N, "Background"); });
+    Dict.handle("External", [&](Node &N) {
+      F.External.emplace();
+      parse(*F.External, N);
+    });
+    Dict.parse(N);
+  }
+
+  void parse(Fragment::IndexBlock::ExternalBlock &F, Node &N) {
+    DictParser Dict("External", this);
+    Dict.handle("File", [&](Node &N) { F.File = scalarValue(N, "File"); });
+    Dict.handle("Server", [&](Node &N) {
+#if CLANGD_ENABLE_REMOTE
+      F.Server = scalarValue(N, "Server");
+#else
+      warning("Remote index support isn't enabled for this clangd.", N);
+#endif
+    });
+    Dict.handle("MountPoint",
+                [&](Node &N) { F.MountPoint = scalarValue(N, "MountPoint"); });
     Dict.parse(N);
   }
 
diff --git a/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp b/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
--- a/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ConfigYAMLTests.cpp
@@ -9,7 +9,9 @@
 #include "Annotations.h"
 #include "ConfigFragment.h"
 #include "ConfigTesting.h"
+#include "Features.inc"
 #include "Protocol.h"
+#include "llvm/ADT/StringRef.h"
 #include "llvm/Support/SMLoc.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/SourceMgr.h"
@@ -124,6 +126,34 @@
   ASSERT_THAT(Results, IsEmpty());
 }
 
+TEST(ParseYAML, ExternalBlock) {
+  CapturedDiags Diags;
+  Annotations YAML(R"yaml(
+Index:
+  External:
+    File: "foo"
+    Server: ^"bar"
+    MountPoint: "baz"
+  )yaml");
+  auto Results =
+      Fragment::parseYAML(YAML.code(), "config.yaml", Diags.callback());
+  ASSERT_EQ(Results.size(), 1u);
+  ASSERT_TRUE(Results[0].Index.External);
+  EXPECT_THAT(*Results[0].Index.External->File, Val("foo"));
+  EXPECT_THAT(*Results[0].Index.External->MountPoint, Val("baz"));
+#if CLANGD_ENABLE_REMOTE
+  ASSERT_THAT(Diags.Diagnostics, IsEmpty());
+  EXPECT_THAT(*Results[0].Index.External->Server, Val("bar"));
+#else
+  EXPECT_FALSE(Results[0].Index.External->Server);
+  EXPECT_THAT(
+      Diags.Diagnostics,
+      ElementsAre(AllOf(
+          DiagMessage("Remote index support isn't enabled for this clangd."),
+          DiagPos(YAML.point()), DiagKind(llvm::SourceMgr::DK_Warning))));
+#endif
+}
+
 } // namespace
 } // namespace config
 } // namespace clangd