diff --git a/clang-tools-extra/clangd/CMakeLists.txt b/clang-tools-extra/clangd/CMakeLists.txt
--- a/clang-tools-extra/clangd/CMakeLists.txt
+++ b/clang-tools-extra/clangd/CMakeLists.txt
@@ -59,6 +59,7 @@
 endif()
 
 include_directories(BEFORE "${CMAKE_CURRENT_BINARY_DIR}/../clang-tidy")
+include_directories(BEFORE "${CMAKE_CURRENT_SOURCE_DIR}/../include-cleaner/include")
 
 add_clang_library(clangDaemon
   AST.cpp
@@ -162,6 +163,7 @@
   clangDriver
   clangFormat
   clangFrontend
+  clangIncludeCleaner
   clangIndex
   clangLex
   clangSema
diff --git a/clang-tools-extra/clangd/Config.h b/clang-tools-extra/clangd/Config.h
--- a/clang-tools-extra/clangd/Config.h
+++ b/clang-tools-extra/clangd/Config.h
@@ -88,7 +88,13 @@
     bool StandardLibrary = true;
   } Index;
 
-  enum UnusedIncludesPolicy { Strict, None };
+  enum UnusedIncludesPolicy {
+    /// Diagnose unused includes.
+    Strict,
+    None,
+    /// The same as Strict, but using the include-cleaner library.
+    Experiment,
+  };
   /// Controls warnings and errors when parsing code.
   struct {
     bool SuppressAll = false;
diff --git a/clang-tools-extra/clangd/ConfigCompile.cpp b/clang-tools-extra/clangd/ConfigCompile.cpp
--- a/clang-tools-extra/clangd/ConfigCompile.cpp
+++ b/clang-tools-extra/clangd/ConfigCompile.cpp
@@ -431,11 +431,13 @@
           });
 
     if (F.UnusedIncludes)
-      if (auto Val = compileEnum<Config::UnusedIncludesPolicy>(
-                         "UnusedIncludes", **F.UnusedIncludes)
-                         .map("Strict", Config::UnusedIncludesPolicy::Strict)
-                         .map("None", Config::UnusedIncludesPolicy::None)
-                         .value())
+      if (auto Val =
+              compileEnum<Config::UnusedIncludesPolicy>("UnusedIncludes",
+                                                        **F.UnusedIncludes)
+                  .map("Strict", Config::UnusedIncludesPolicy::Strict)
+                  .map("Experiment", Config::UnusedIncludesPolicy::Experiment)
+                  .map("None", Config::UnusedIncludesPolicy::None)
+                  .value())
         Out.Apply.push_back([Val](const Params &, Config &C) {
           C.Diagnostics.UnusedIncludes = *Val;
         });
diff --git a/clang-tools-extra/clangd/IncludeCleaner.h b/clang-tools-extra/clangd/IncludeCleaner.h
--- a/clang-tools-extra/clangd/IncludeCleaner.h
+++ b/clang-tools-extra/clangd/IncludeCleaner.h
@@ -97,6 +97,10 @@
           const llvm::StringSet<> &ReferencedPublicHeaders);
 
 std::vector<const Inclusion *> computeUnusedIncludes(ParsedAST &AST);
+// The same as computeUnusedIncludes, but it is an experimental and
+// include-cleaner-lib-based implementation.
+std::vector<const Inclusion *>
+computeUnusedIncludesExperimental(ParsedAST &AST);
 
 std::vector<Diag> issueUnusedIncludesDiagnostics(ParsedAST &AST,
                                                  llvm::StringRef Code);
diff --git a/clang-tools-extra/clangd/IncludeCleaner.cpp b/clang-tools-extra/clangd/IncludeCleaner.cpp
--- a/clang-tools-extra/clangd/IncludeCleaner.cpp
+++ b/clang-tools-extra/clangd/IncludeCleaner.cpp
@@ -12,6 +12,8 @@
 #include "ParsedAST.h"
 #include "Protocol.h"
 #include "SourceCode.h"
+#include "clang-include-cleaner/Analysis.h"
+#include "clang-include-cleaner/Types.h"
 #include "index/CanonicalIncludes.h"
 #include "support/Logger.h"
 #include "support/Trace.h"
@@ -458,6 +460,9 @@
   return TranslatedHeaderIDs;
 }
 
+// This is the original clangd-own implementation for computing unused
+// #includes. Eventually it will be deprecated and replaced by the
+// include-cleaner-lib-based implementation.
 std::vector<const Inclusion *> computeUnusedIncludes(ParsedAST &AST) {
   const auto &SM = AST.getSourceManager();
 
@@ -469,11 +474,62 @@
       translateToHeaderIDs(ReferencedFiles, AST.getIncludeStructure(), SM);
   return getUnused(AST, ReferencedHeaders, ReferencedFiles.SpelledUmbrellas);
 }
+std::vector<const Inclusion *> computeUnusedIncludesExperimental(ParsedAST &AST) {
+   const auto &SM = AST.getSourceManager();
+   const auto &Includes = AST.getIncludeStructure();
+   // FIXME: this map should probably be in IncludeStructure.
+   llvm::StringMap<llvm::SmallVector<IncludeStructure::HeaderID>> BySpelling;
+   for (const auto &Inc : Includes.MainFileIncludes) {
+    if (Inc.HeaderID)
+      BySpelling.try_emplace(Inc.Written)
+          .first->second.push_back(
+              static_cast<IncludeStructure::HeaderID>(*Inc.HeaderID));
+   }
+   // FIXME: !!this is a hacky way to collect macro references.
+   std::vector<include_cleaner::SymbolReference> Macros;
+    auto& PP = AST.getPreprocessor();
+   for (const syntax::Token &Tok :
+        AST.getTokens().spelledTokens(SM.getMainFileID())) {
+    auto Macro = locateMacroAt(Tok, PP);
+    if (!Macro)
+      continue;
+    if (auto DefLoc = Macro->Info->getDefinitionLoc(); DefLoc.isValid())
+      Macros.push_back(
+          {Tok.location(),
+           include_cleaner::Macro{/*Name=*/PP.getIdentifierInfo(Tok.text(SM)),
+                                  DefLoc},
+           include_cleaner::RefType::Explicit});
+   }
+   llvm::DenseSet<IncludeStructure::HeaderID> Used;
+   include_cleaner::walkUsed(
+       AST.getLocalTopLevelDecls(), /*MacroRefs=*/Macros,
+       AST.getPragmaIncludes(), SM,
+       [&](const include_cleaner::SymbolReference &Ref,
+           llvm::ArrayRef<include_cleaner::Header> Providers) {
+         for (const auto &H : Providers) {
+           switch (H.kind()) {
+           case include_cleaner::Header::Physical:
+             if (auto HeaderID = Includes.getID(H.physical()))
+               Used.insert(*HeaderID);
+             break;
+           case include_cleaner::Header::Standard:
+             for (auto HeaderID : Includes.StdlibHeaders.lookup(H.standard()))
+               Used.insert(HeaderID);
+             break;
+           case include_cleaner::Header::Verbatim:
+             for (auto HeaderID : BySpelling.lookup(H.verbatim()))
+               Used.insert(HeaderID);
+             break;
+           }
+         }
+       });
+   return getUnused(AST, Used, /*ReferencedPublicHeaders*/{});
+}
 
 std::vector<Diag> issueUnusedIncludesDiagnostics(ParsedAST &AST,
                                                  llvm::StringRef Code) {
   const Config &Cfg = Config::current();
-  if (Cfg.Diagnostics.UnusedIncludes != Config::UnusedIncludesPolicy::Strict ||
+  if (Cfg.Diagnostics.UnusedIncludes == Config::UnusedIncludesPolicy::None ||
       Cfg.Diagnostics.SuppressAll ||
       Cfg.Diagnostics.Suppress.contains("unused-includes"))
     return {};
@@ -487,7 +543,11 @@
           .getFileEntryRefForID(AST.getSourceManager().getMainFileID())
           ->getName()
           .str();
-  for (const auto *Inc : computeUnusedIncludes(AST)) {
+  const auto &UnusedIncludes =
+      Cfg.Diagnostics.UnusedIncludes == Config::UnusedIncludesPolicy::Experiment
+          ? computeUnusedIncludesExperimental(AST)
+          : computeUnusedIncludes(AST);
+  for (const auto *Inc : UnusedIncludes) {
     Diag D;
     D.Message =
         llvm::formatv("included header {0} is not used directly",
diff --git a/clang-tools-extra/clangd/ParsedAST.h b/clang-tools-extra/clangd/ParsedAST.h
--- a/clang-tools-extra/clangd/ParsedAST.h
+++ b/clang-tools-extra/clangd/ParsedAST.h
@@ -25,6 +25,7 @@
 #include "Diagnostics.h"
 #include "Headers.h"
 #include "Preamble.h"
+#include "clang-include-cleaner/Record.h"
 #include "index/CanonicalIncludes.h"
 #include "support/Path.h"
 #include "clang/Frontend/FrontendAction.h"
@@ -107,6 +108,8 @@
   /// (!) does not have tokens from the preamble.
   const syntax::TokenBuffer &getTokens() const { return Tokens; }
 
+  const include_cleaner::PragmaIncludes *getPragmaIncludes() const;
+
   /// Returns the version of the ParseInputs this AST was built from.
   llvm::StringRef version() const { return Version; }
 
diff --git a/clang-tools-extra/clangd/ParsedAST.cpp b/clang-tools-extra/clangd/ParsedAST.cpp
--- a/clang-tools-extra/clangd/ParsedAST.cpp
+++ b/clang-tools-extra/clangd/ParsedAST.cpp
@@ -23,6 +23,7 @@
 #include "Preamble.h"
 #include "SourceCode.h"
 #include "TidyProvider.h"
+#include "clang-include-cleaner/Record.h"
 #include "index/CanonicalIncludes.h"
 #include "index/Index.h"
 #include "index/Symbol.h"
@@ -801,6 +802,12 @@
   assert(this->Action);
 }
 
+const include_cleaner::PragmaIncludes *ParsedAST::getPragmaIncludes() const {
+  if (!Preamble)
+    return nullptr;
+  return &Preamble->Pragmas;
+}
+
 std::optional<llvm::StringRef> ParsedAST::preambleVersion() const {
   if (!Preamble)
     return std::nullopt;
diff --git a/clang-tools-extra/clangd/Preamble.h b/clang-tools-extra/clangd/Preamble.h
--- a/clang-tools-extra/clangd/Preamble.h
+++ b/clang-tools-extra/clangd/Preamble.h
@@ -27,6 +27,7 @@
 #include "Diagnostics.h"
 #include "FS.h"
 #include "Headers.h"
+#include "clang-include-cleaner/Record.h"
 #include "index/CanonicalIncludes.h"
 #include "support/Path.h"
 #include "clang/Frontend/CompilerInvocation.h"
@@ -57,6 +58,8 @@
   // Processes like code completions and go-to-definitions will need #include
   // information, and their compile action skips preamble range.
   IncludeStructure Includes;
+  // Captures #include-mapping information in #included headers.
+  include_cleaner::PragmaIncludes Pragmas;
   // Macros defined in the preamble section of the main file.
   // Users care about headers vs main-file, not preamble vs non-preamble.
   // These should be treated as main-file entities e.g. for code completion.
diff --git a/clang-tools-extra/clangd/Preamble.cpp b/clang-tools-extra/clangd/Preamble.cpp
--- a/clang-tools-extra/clangd/Preamble.cpp
+++ b/clang-tools-extra/clangd/Preamble.cpp
@@ -11,6 +11,7 @@
 #include "Config.h"
 #include "Headers.h"
 #include "SourceCode.h"
+#include "clang-include-cleaner/Record.h"
 #include "support/Logger.h"
 #include "support/ThreadsafeFS.h"
 #include "support/Trace.h"
@@ -77,6 +78,9 @@
 
   std::vector<PragmaMark> takeMarks() { return std::move(Marks); }
 
+  include_cleaner::PragmaIncludes takePragmaIncludes() {
+    return std::move(Pragmas);
+  }
   CanonicalIncludes takeCanonicalIncludes() { return std::move(CanonIncludes); }
 
   bool isMainFileIncludeGuarded() const { return IsMainFileIncludeGuarded; }
@@ -118,6 +122,9 @@
     LangOpts = &CI.getLangOpts();
     SourceMgr = &CI.getSourceManager();
     Includes.collect(CI);
+    if (Config::current().Diagnostics.UnusedIncludes ==
+        Config::UnusedIncludesPolicy::Experiment)
+      Pragmas.record(CI);
     if (BeforeExecuteCallback)
       BeforeExecuteCallback(CI);
   }
@@ -187,6 +194,7 @@
   PreambleParsedCallback ParsedCallback;
   IncludeStructure Includes;
   CanonicalIncludes CanonIncludes;
+  include_cleaner::PragmaIncludes Pragmas;
   MainFileMacros Macros;
   std::vector<PragmaMark> Marks;
   bool IsMainFileIncludeGuarded = false;
@@ -560,6 +568,7 @@
     Result->CompileCommand = Inputs.CompileCommand;
     Result->Diags = std::move(Diags);
     Result->Includes = CapturedInfo.takeIncludes();
+    Result->Pragmas = CapturedInfo.takePragmaIncludes();
     Result->Macros = CapturedInfo.takeMacros();
     Result->Marks = CapturedInfo.takeMarks();
     Result->CanonIncludes = CapturedInfo.takeCanonicalIncludes();
diff --git a/clang-tools-extra/clangd/unittests/IncludeCleanerTests.cpp b/clang-tools-extra/clangd/unittests/IncludeCleanerTests.cpp
--- a/clang-tools-extra/clangd/unittests/IncludeCleanerTests.cpp
+++ b/clang-tools-extra/clangd/unittests/IncludeCleanerTests.cpp
@@ -342,6 +342,8 @@
   auto AST = TU.build();
   EXPECT_THAT(computeUnusedIncludes(AST),
               ElementsAre(Pointee(writtenInclusion("<queue>"))));
+  EXPECT_THAT(computeUnusedIncludesExperimental(AST),
+              ElementsAre(Pointee(writtenInclusion("<queue>"))));
 }
 
 TEST(IncludeCleaner, GetUnusedHeaders) {
@@ -377,6 +379,10 @@
       computeUnusedIncludes(AST),
       UnorderedElementsAre(Pointee(writtenInclusion("\"unused.h\"")),
                            Pointee(writtenInclusion("\"dir/unused.h\""))));
+  EXPECT_THAT(
+      computeUnusedIncludesExperimental(AST),
+      UnorderedElementsAre(Pointee(writtenInclusion("\"unused.h\"")),
+                           Pointee(writtenInclusion("\"dir/unused.h\""))));
 }
 
 TEST(IncludeCleaner, VirtualBuffers) {
@@ -531,6 +537,9 @@
     // IWYU pragma: private, include "public.h"
     void foo() {}
   )cpp");
+  Config Cfg;
+  Cfg.Diagnostics.UnusedIncludes = Config::Experiment;
+  WithContextValue Ctx(Config::Key, std::move(Cfg));
   ParsedAST AST = TU.build();
 
   auto ReferencedFiles = findReferencedFiles(
@@ -545,6 +554,7 @@
       ReferencedFiles.User.contains(AST.getSourceManager().getMainFileID()));
   EXPECT_THAT(AST.getDiagnostics(), llvm::ValueIs(IsEmpty()));
   EXPECT_THAT(computeUnusedIncludes(AST), IsEmpty());
+  EXPECT_THAT(computeUnusedIncludesExperimental(AST), IsEmpty());
 }
 
 TEST(IncludeCleaner, RecursiveInclusion) {
@@ -573,6 +583,7 @@
 
   EXPECT_THAT(AST.getDiagnostics(), llvm::ValueIs(IsEmpty()));
   EXPECT_THAT(computeUnusedIncludes(AST), IsEmpty());
+  EXPECT_THAT(computeUnusedIncludesExperimental(AST), IsEmpty());
 }
 
 TEST(IncludeCleaner, IWYUPragmaExport) {
@@ -597,6 +608,7 @@
   // FIXME: This is not correct: foo.h is unused but is not diagnosed as such
   // because we ignore headers with IWYU export pragmas for now.
   EXPECT_THAT(computeUnusedIncludes(AST), IsEmpty());
+  EXPECT_THAT(computeUnusedIncludesExperimental(AST), IsEmpty());
 }
 
 TEST(IncludeCleaner, NoDiagsForObjC) {