diff --git a/clang-tools-extra/clangd/ClangdLSPServer.h b/clang-tools-extra/clangd/ClangdLSPServer.h
--- a/clang-tools-extra/clangd/ClangdLSPServer.h
+++ b/clang-tools-extra/clangd/ClangdLSPServer.h
@@ -24,6 +24,7 @@
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/JSON.h"
 #include <chrono>
+#include <cstddef>
 #include <memory>
 
 namespace clang {
@@ -141,6 +142,27 @@
   void onSemanticTokens(const SemanticTokensParams &, Callback<SemanticTokens>);
   void onSemanticTokensDelta(const SemanticTokensDeltaParams &,
                              Callback<SemanticTokensOrDelta>);
+  /// This is a clangd extension. Provides a json tree representing memory usage
+  /// hierarchy. Keys starting with an underscore(_) represent leaves, e.g.
+  /// _total or _self for memory usage of whole subtree or only that specific
+  /// node in bytes. All other keys represents children. An example:
+  ///   {
+  ///     "_self": 0,
+  ///     "_total": 8,
+  ///     "child1": {
+  ///       "_self": 4,
+  ///       "_total": 4,
+  ///     }
+  ///     "child2": {
+  ///       "_self": 2,
+  ///       "_total": 4,
+  ///       "child_deep": {
+  ///         "_self": 2,
+  ///         "_total": 2,
+  ///       }
+  ///     }
+  ///   }
+  void onDumpMemoryTree(const NoParams &, Callback<llvm::json::Value>);
 
   std::vector<Fix> getFixes(StringRef File, const clangd::Diagnostic &D);
 
diff --git a/clang-tools-extra/clangd/ClangdLSPServer.cpp b/clang-tools-extra/clangd/ClangdLSPServer.cpp
--- a/clang-tools-extra/clangd/ClangdLSPServer.cpp
+++ b/clang-tools-extra/clangd/ClangdLSPServer.cpp
@@ -36,8 +36,11 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/SHA1.h"
 #include "llvm/Support/ScopedPrinter.h"
+#include "llvm/Support/raw_ostream.h"
 #include <chrono>
 #include <cstddef>
+#include <cstdint>
+#include <functional>
 #include <memory>
 #include <mutex>
 #include <string>
@@ -1383,6 +1386,33 @@
       });
 }
 
+void ClangdLSPServer::onDumpMemoryTree(const NoParams &,
+                                       Callback<llvm::json::Value> Reply) {
+  llvm::BumpPtrAllocator Alloc;
+  MemoryTree MT(&Alloc);
+  profile(MT);
+
+  std::function<int64_t(const MemoryTree &, llvm::json::Object &)> DumpTree =
+      [&](const MemoryTree &MT, llvm::json::Object &Out) {
+        int64_t Total = MT.self();
+        Out["_self"] = Total;
+        for (const auto &Entry : MT.children()) {
+          auto *Child = Out.try_emplace(Entry.getFirst(), llvm::json::Object{})
+                            .first->getSecond()
+                            .getAsObject();
+          assert(Child);
+          Total += DumpTree(Entry.getSecond(), *Child);
+        }
+        Out["_total"] = Total;
+        return Total;
+      };
+
+  llvm::json::Object Out;
+  DumpTree(MT, Out);
+
+  Reply(std::move(Out));
+}
+
 ClangdLSPServer::ClangdLSPServer(class Transport &Transp,
                                  const ThreadsafeFS &TFS,
                                  const ClangdLSPServer::Options &Opts)
@@ -1425,6 +1455,7 @@
   MsgHandler->bind("textDocument/documentLink", &ClangdLSPServer::onDocumentLink);
   MsgHandler->bind("textDocument/semanticTokens/full", &ClangdLSPServer::onSemanticTokens);
   MsgHandler->bind("textDocument/semanticTokens/full/delta", &ClangdLSPServer::onSemanticTokensDelta);
+  MsgHandler->bind("$/dumpMemoryTree", &ClangdLSPServer::onDumpMemoryTree);
   if (Opts.FoldingRanges)
     MsgHandler->bind("textDocument/foldingRange", &ClangdLSPServer::onFoldingRange);
   // clang-format on
diff --git a/clang-tools-extra/clangd/test/memory_tree.test b/clang-tools-extra/clangd/test/memory_tree.test
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/clangd/test/memory_tree.test
@@ -0,0 +1,81 @@
+# RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
+{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
+---
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///main.cpp","languageId":"cpp","version":1,"text":"void func() {}"}}}
+---
+{"jsonrpc":"2.0","id":1,"method":"$/dumpMemoryTree","params":{}}
+# CHECK:        "id": 1,
+# CHECK-NEXT:   "jsonrpc": "2.0",
+# CHECK-NEXT:   "result": {
+# CHECK-NEXT:     "_self": {{[0-9]+}},
+# CHECK-NEXT:     "_total": {{[0-9]+}},
+# CHECK-NEXT:     "clangd_server": {
+# CHECK-NEXT:       "_self": {{[0-9]+}},
+# CHECK-NEXT:       "_total": {{[0-9]+}},
+# CHECK-NEXT:       "dynamic_index": {
+# CHECK-NEXT:         "_self": {{[0-9]+}},
+# CHECK-NEXT:         "_total": {{[0-9]+}},
+# CHECK-NEXT:         "main_file": {
+# CHECK-NEXT:           "_self": {{[0-9]+}},
+# CHECK-NEXT:           "_total": {{[0-9]+}},
+# CHECK-NEXT:           "index": {
+# CHECK-NEXT:             "_self": {{[0-9]+}},
+# CHECK-NEXT:             "_total": {{[0-9]+}}
+# CHECK-NEXT:           },
+# CHECK-NEXT:           "symbols": {
+# CHECK-NEXT:             "{{.*}}main.cpp": {
+# CHECK-NEXT:               "_self": {{[0-9]+}},
+# CHECK-NEXT:               "_total": {{[0-9]+}},
+# CHECK-NEXT:               "references": {
+# CHECK-NEXT:                 "_self": {{[0-9]+}},
+# CHECK-NEXT:                 "_total": {{[0-9]+}}
+# CHECK-NEXT:               },
+# CHECK-NEXT:               "relations": {
+# CHECK-NEXT:                 "_self": {{[0-9]+}},
+# CHECK-NEXT:                 "_total": {{[0-9]+}}
+# CHECK-NEXT:               },
+# CHECK-NEXT:               "symbols": {
+# CHECK-NEXT:                 "_self": {{[0-9]+}},
+# CHECK-NEXT:                 "_total": {{[0-9]+}}
+# CHECK-NEXT:               }
+# CHECK-NEXT:             },
+# CHECK-NEXT:             "_self": {{[0-9]+}},
+# CHECK-NEXT:             "_total": {{[0-9]+}}
+# CHECK-NEXT:           }
+# CHECK-NEXT:         },
+# CHECK-NEXT:         "preamble": {
+# CHECK-NEXT:           "_self": {{[0-9]+}},
+# CHECK-NEXT:           "_total": {{[0-9]+}},
+# CHECK-NEXT:           "index": {
+# CHECK-NEXT:             "_self": {{[0-9]+}},
+# CHECK-NEXT:             "_total": {{[0-9]+}}
+# CHECK-NEXT:           },
+# CHECK-NEXT:           "symbols": {
+# CHECK-NEXT:             "_self": {{[0-9]+}},
+# CHECK-NEXT:             "_total": {{[0-9]+}}
+# CHECK-NEXT:           }
+# CHECK-NEXT:         }
+# CHECK-NEXT:       },
+# CHECK-NEXT:       "tuscheduler": {
+# CHECK-NEXT:         "{{.*}}main.cpp": {
+# CHECK-NEXT:           "_self": {{[0-9]+}},
+# CHECK-NEXT:           "_total": {{[0-9]+}},
+# CHECK-NEXT:           "ast": {
+# CHECK-NEXT:             "_self": {{[0-9]+}},
+# CHECK-NEXT:             "_total": {{[0-9]+}}
+# CHECK-NEXT:           },
+# CHECK-NEXT:           "preamble": {
+# CHECK-NEXT:             "_self": {{[0-9]+}},
+# CHECK-NEXT:             "_total": {{[0-9]+}}
+# CHECK-NEXT:           }
+# CHECK-NEXT:         },
+# CHECK-NEXT:         "_self": {{[0-9]+}},
+# CHECK-NEXT:         "_total": {{[0-9]+}}
+# CHECK-NEXT:       }
+# CHECK-NEXT:     }
+# CHECK-NEXT:   }
+---
+{"jsonrpc":"2.0","id":3,"method":"shutdown"}
+---
+{"jsonrpc":"2.0","method":"exit"}
+