diff --git a/clang-tools-extra/clangd/ClangdUnit.h b/clang-tools-extra/clangd/ClangdUnit.h
--- a/clang-tools-extra/clangd/ClangdUnit.h
+++ b/clang-tools-extra/clangd/ClangdUnit.h
@@ -116,6 +116,7 @@
   const IncludeStructure &getIncludeStructure() const;
   const CanonicalIncludes &getCanonicalIncludes() const;
 
+  const std::vector<SourceLocation> &getMainFileMacroExpansionLocations() const;
   /// Tokens recorded while parsing the main file.
   /// (!) does not have tokens from the preamble.
   const syntax::TokenBuffer &getTokens() const { return Tokens; }
@@ -124,6 +125,7 @@
   ParsedAST(std::shared_ptr<const PreambleData> Preamble,
             std::unique_ptr<CompilerInstance> Clang,
             std::unique_ptr<FrontendAction> Action, syntax::TokenBuffer Tokens,
+            std::vector<SourceLocation> MainFileMacroExpLocs,
             std::vector<Decl *> LocalTopLevelDecls, std::vector<Diag> Diags,
             IncludeStructure Includes, CanonicalIncludes CanonIncludes);
 
@@ -143,6 +145,8 @@
   ///   - Does not have spelled or expanded tokens for files from preamble.
   syntax::TokenBuffer Tokens;
 
+  /// All macro expansion locations in the main file.
+  std::vector<SourceLocation> MainFileMacroExpLocs;
   // Data, stored after parsing.
   std::vector<Diag> Diags;
   // Top-level decls inside the current file. Not that this does not include
diff --git a/clang-tools-extra/clangd/ClangdUnit.cpp b/clang-tools-extra/clangd/ClangdUnit.cpp
--- a/clang-tools-extra/clangd/ClangdUnit.cpp
+++ b/clang-tools-extra/clangd/ClangdUnit.cpp
@@ -32,6 +32,7 @@
 #include "clang/Index/IndexingAction.h"
 #include "clang/Lex/Lexer.h"
 #include "clang/Lex/MacroInfo.h"
+#include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Sema/Sema.h"
@@ -103,6 +104,24 @@
   std::vector<Decl *> TopLevelDecls;
 };
 
+class CollectMainFileMacroExpansions : public PPCallbacks {
+  const SourceManager &SM;
+  std::vector<SourceLocation> &MainFileMacroLocs;
+
+public:
+  CollectMainFileMacroExpansions(const SourceManager &SM,
+                                 std::vector<SourceLocation> &MainFileMacroLocs)
+      : SM(SM), MainFileMacroLocs(MainFileMacroLocs) {}
+
+  virtual void MacroExpands(const Token &MacroNameTok,
+                            const MacroDefinition &MD, SourceRange Range,
+                            const MacroArgs *Args) {
+    SourceLocation L = MacroNameTok.getLocation();
+    if (isInsideMainFile(SM.getSpellingLoc(L), SM))
+      MainFileMacroLocs.push_back(L);
+  }
+};
+
 class CollectMainFileMacros : public PPCallbacks {
 public:
   explicit CollectMainFileMacros(const SourceManager &SM,
@@ -414,6 +433,11 @@
   // (We can't *just* use the replayed includes, they don't have Resolved path).
   Clang->getPreprocessor().addPPCallbacks(
       collectIncludeStructureCallback(Clang->getSourceManager(), &Includes));
+  // Collect the macro expansions in the main file.
+  std::vector<SourceLocation> MainFileMacroExpLocs;
+  Clang->getPreprocessor().addPPCallbacks(
+      std::make_unique<CollectMainFileMacroExpansions>(
+          Clang->getSourceManager(), MainFileMacroExpLocs));
 
   // Copy over the includes from the preamble, then combine with the
   // non-preamble includes below.
@@ -462,7 +486,8 @@
   if (Preamble)
     Diags.insert(Diags.begin(), Preamble->Diags.begin(), Preamble->Diags.end());
   return ParsedAST(std::move(Preamble), std::move(Clang), std::move(Action),
-                   std::move(Tokens), std::move(ParsedDecls), std::move(Diags),
+                   std::move(Tokens), std::move(MainFileMacroExpLocs),
+                   std::move(ParsedDecls), std::move(Diags),
                    std::move(Includes), std::move(CanonIncludes));
 }
 
@@ -501,6 +526,11 @@
   return LocalTopLevelDecls;
 }
 
+const std::vector<SourceLocation> &
+ParsedAST::getMainFileMacroExpansionLocations() const {
+  return MainFileMacroExpLocs;
+}
+
 const std::vector<Diag> &ParsedAST::getDiagnostics() const { return Diags; }
 
 std::size_t ParsedAST::getUsedBytes() const {
@@ -557,11 +587,13 @@
                      std::unique_ptr<CompilerInstance> Clang,
                      std::unique_ptr<FrontendAction> Action,
                      syntax::TokenBuffer Tokens,
+                     std::vector<SourceLocation> MainFileMacroExpLocs,
                      std::vector<Decl *> LocalTopLevelDecls,
                      std::vector<Diag> Diags, IncludeStructure Includes,
                      CanonicalIncludes CanonIncludes)
     : Preamble(std::move(Preamble)), Clang(std::move(Clang)),
       Action(std::move(Action)), Tokens(std::move(Tokens)),
+      MainFileMacroExpLocs(std::move(MainFileMacroExpLocs)),
       Diags(std::move(Diags)),
       LocalTopLevelDecls(std::move(LocalTopLevelDecls)),
       Includes(std::move(Includes)), CanonIncludes(std::move(CanonIncludes)) {
diff --git a/clang-tools-extra/clangd/unittests/ClangdUnitTests.cpp b/clang-tools-extra/clangd/unittests/ClangdUnitTests.cpp
--- a/clang-tools-extra/clangd/unittests/ClangdUnitTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ClangdUnitTests.cpp
@@ -244,6 +244,28 @@
   EXPECT_EQ(T.expandedTokens().drop_back().back().text(SM), "}");
 }
 
+TEST(ClangdUnitTest, CollectsMainFileMacroExpansions) {
+  Annotations TestCase(R"cpp(
+    #define MACRO_ARGS(X, Y) X Y
+    ^MACRO_EXP(int A);
+    ^MACRO_ARGS(^MACRO_ARGS(^MACRO_EXP(int), A), ^MACRO_EXP(= 2));
+  )cpp");
+  auto TU = TestTU::withCode(TestCase.code());
+  TU.HeaderCode = R"cpp(
+    #define INNER_MACRO_EXP(X) X
+    #define MACRO_EXP(X) INNER_MACRO_EXP(X)
+    MACRO_EXP(int B);
+  )cpp";
+  ParsedAST AST = TU.build();
+  const std::vector<SourceLocation> &MacroExpansionLocations =
+      AST.getMainFileMacroExpansionLocations();
+  std::vector<Position> MacroExpansionPositions(MacroExpansionLocations.size());
+  for (int I = 0, End = MacroExpansionLocations.size(); I < End; ++I)
+    MacroExpansionPositions[I] =
+        sourceLocToPosition(AST.getSourceManager(), MacroExpansionLocations[I]);
+  EXPECT_EQ(MacroExpansionPositions, TestCase.points());
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang