Index: clang-tools-extra/clangd/index/SymbolCollector.cpp
===================================================================
--- clang-tools-extra/clangd/index/SymbolCollector.cpp
+++ clang-tools-extra/clangd/index/SymbolCollector.cpp
@@ -374,13 +374,17 @@
 
   const auto &SM = PP->getSourceManager();
   auto DefLoc = MI->getDefinitionLoc();
-  if (SM.isInMainFile(SM.getExpansionLoc(DefLoc)))
-    return true;
+  bool IsMainFileSymbol = SM.isInMainFile(SM.getExpansionLoc(DefLoc));
+  
   // Header guards are not interesting in index. Builtin macros don't have
   // useful locations and are not needed for code completions.
   if (MI->isUsedForHeaderGuard() || MI->isBuiltinMacro())
     return true;
 
+  // Also avoid storing predefined macros like __DBL_MIN__.
+  if (IsMainFileSymbol && SM.isWrittenInBuiltinFile(DefLoc))
+    return true;
+
   // Mark the macro as referenced if this is a reference coming from the main
   // file. The macro may not be an interesting symbol, but it's cheaper to check
   // at the end.
@@ -405,7 +409,8 @@
   Symbol S;
   S.ID = std::move(*ID);
   S.Name = Name->getName();
-  S.Flags |= Symbol::IndexedForCodeCompletion;
+  if (!IsMainFileSymbol)
+    S.Flags |= Symbol::IndexedForCodeCompletion;
   S.SymInfo = index::getSymbolInfoForMacro(*MI);
   std::string FileURI;
   // FIXME: use the result to filter out symbols.
Index: clang-tools-extra/unittests/clangd/FindSymbolsTests.cpp
===================================================================
--- clang-tools-extra/unittests/clangd/FindSymbolsTests.cpp
+++ clang-tools-extra/unittests/clangd/FindSymbolsTests.cpp
@@ -88,13 +88,16 @@
 
 } // namespace
 
-TEST_F(WorkspaceSymbolsTest, NoMacro) {
+TEST_F(WorkspaceSymbolsTest, Macros) {
   addFile("foo.cpp", R"cpp(
       #define MACRO X
       )cpp");
 
-  // Macros are not in the index.
-  EXPECT_THAT(getSymbols("macro"), IsEmpty());
+  // LSP's SymbolKind doesn't have a "Macro" kind, and
+  // indexSymbolKindToSymbolKind() currently maps macros
+  // to SymbolKind::String.
+  EXPECT_THAT(getSymbols("macro"),
+              ElementsAre(AllOf(QName("MACRO"), WithKind(SymbolKind::String))));
 }
 
 TEST_F(WorkspaceSymbolsTest, NoLocals) {
Index: clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
===================================================================
--- clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
+++ clang-tools-extra/unittests/clangd/SymbolCollectorTests.cpp
@@ -1053,13 +1053,13 @@
 
     MAC(p);
   )");
-  const std::string Main = R"(
-    #define MAIN 1  // not indexed
+  Annotations Main(R"(
+    #define $main[[MAIN]] 1
     USED(t);
-  )";
+  )");
   CollectorOpts.CountReferences = true;
   CollectorOpts.CollectMacro = true;
-  runSymbolCollector(Header.code(), Main);
+  runSymbolCollector(Header.code(), Main.code());
   EXPECT_THAT(Symbols,
               UnorderedElementsAre(QName("p"), QName("t"),
                                    AllOf(QName("X"), DeclURI(TestHeaderURI),
@@ -1067,7 +1067,9 @@
                                    AllOf(Labeled("MAC(x)"), RefCount(0),
                                          DeclRange(Header.range("mac"))),
                                    AllOf(Labeled("USED(y)"), RefCount(1),
-                                         DeclRange(Header.range("used")))));
+                                         DeclRange(Header.range("used"))),
+                                   AllOf(Labeled("MAIN"), RefCount(0),
+                                         DeclRange(Main.range("main")))));
 }
 
 TEST_F(SymbolCollectorTest, DeprecatedSymbols) {