diff --git a/clang-tools-extra/clangd/ClangdServer.h b/clang-tools-extra/clangd/ClangdServer.h
--- a/clang-tools-extra/clangd/ClangdServer.h
+++ b/clang-tools-extra/clangd/ClangdServer.h
@@ -359,6 +359,7 @@
   std::unique_ptr<BackgroundIndex> BackgroundIdx;
   // Storage for merged views of the various indexes.
   std::vector<std::unique_ptr<SymbolIndex>> MergedIdx;
+  BuildSystemProvider BSP;
 
   // When set, provides clang-tidy options for a specific file.
   TidyProviderRef ClangTidyProvider;
diff --git a/clang-tools-extra/clangd/ClangdServer.cpp b/clang-tools-extra/clangd/ClangdServer.cpp
--- a/clang-tools-extra/clangd/ClangdServer.cpp
+++ b/clang-tools-extra/clangd/ClangdServer.cpp
@@ -195,6 +195,7 @@
   Inputs.Opts = std::move(Opts);
   Inputs.Index = Index;
   Inputs.ClangTidyProvider = ClangTidyProvider;
+  Inputs.BS = BSP.get(File);
   bool NewFile = WorkScheduler.update(File, Inputs, WantDiags);
   // If we loaded Foo.h, we want to make sure Foo.cpp is indexed.
   if (NewFile && BackgroundIdx)
diff --git a/clang-tools-extra/clangd/Compiler.h b/clang-tools-extra/clangd/Compiler.h
--- a/clang-tools-extra/clangd/Compiler.h
+++ b/clang-tools-extra/clangd/Compiler.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_COMPILER_H
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_COMPILER_H
 
+#include "BuildSystem.h"
 #include "GlobalCompilationDatabase.h"
 #include "TidyProvider.h"
 #include "index/Index.h"
@@ -54,6 +55,7 @@
   const SymbolIndex *Index = nullptr;
   ParseOptions Opts = ParseOptions();
   TidyProviderRef ClangTidyProvider = {};
+  const BuildSystem *BS = nullptr;
 };
 
 /// Builds compiler invocation that could be used to build AST or preamble.
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
@@ -326,6 +326,8 @@
   trace::Span Tracer("BuildPreamble");
   SPAN_ATTACH(Tracer, "File", FileName);
   StoreDiags PreambleDiagnostics;
+  if (Inputs.BS)
+    PreambleDiagnostics.contributeFixes(missingDependencyFixer(Inputs.BS));
   llvm::IntrusiveRefCntPtr<DiagnosticsEngine> PreambleDiagsEngine =
       CompilerInstance::createDiagnostics(&CI.getDiagnosticOpts(),
                                           &PreambleDiagnostics, false);