diff --git a/clang-tools-extra/clangd/SemanticHighlighting.h b/clang-tools-extra/clangd/SemanticHighlighting.h
--- a/clang-tools-extra/clangd/SemanticHighlighting.h
+++ b/clang-tools-extra/clangd/SemanticHighlighting.h
@@ -72,8 +72,9 @@
   ClassScope,
   FileScope,
   GlobalScope,
+  DefaultLibrary,
 
-  LastModifier = GlobalScope
+  LastModifier = DefaultLibrary
 };
 static_assert(static_cast<unsigned>(HighlightingModifier::LastModifier) < 32,
               "Increase width of modifiers bitfield!");
diff --git a/clang-tools-extra/clangd/SemanticHighlighting.cpp b/clang-tools-extra/clangd/SemanticHighlighting.cpp
--- a/clang-tools-extra/clangd/SemanticHighlighting.cpp
+++ b/clang-tools-extra/clangd/SemanticHighlighting.cpp
@@ -407,6 +407,15 @@
     return WithInactiveLines;
   }
 
+  /// Returns true if `Loc` is considered to be from a default/system library.
+  /// This currently checks the systemness of the file by include type, although
+  /// different heuristics may be used in the future (e.g. sysroot paths).
+  bool InDefaultLibrary(SourceLocation Loc) const {
+    if (!Loc.isValid())
+      return false;
+    return SourceMgr.isInSystemHeader(Loc);
+  }
+
   const HeuristicResolver *getResolver() const { return Resolver; }
 
 private:
@@ -419,7 +428,12 @@
   HighlightingToken InvalidHighlightingToken;
 };
 
-llvm::Optional<HighlightingModifier> scopeModifier(const NamedDecl *D) {
+llvm::Optional<HighlightingModifier>
+scopeModifier(const NamedDecl *D, const HighlightingsBuilder &HB) {
+  if (!D)
+    return llvm::None;
+  if (HB.InDefaultLibrary(D->getLocation()))
+    return HighlightingModifier::DefaultLibrary;
   const DeclContext *DC = D->getDeclContext();
   // Injected "Foo" within the class "Foo" has file scope, not class scope.
   if (auto *R = dyn_cast_or_null<RecordDecl>(D))
@@ -447,15 +461,18 @@
   return HighlightingModifier::GlobalScope;
 }
 
-llvm::Optional<HighlightingModifier> scopeModifier(const Type *T) {
+llvm::Optional<HighlightingModifier>
+scopeModifier(const Type *T, const HighlightingsBuilder &HB) {
   if (!T)
     return llvm::None;
   if (T->isBuiltinType())
-    return HighlightingModifier::GlobalScope;
+    return HighlightingModifier::DefaultLibrary;
   if (auto *TD = dyn_cast<TemplateTypeParmType>(T))
-    return scopeModifier(TD->getDecl());
+    return scopeModifier(TD->getDecl(), HB);
   if (auto *TD = T->getAsTagDecl())
-    return scopeModifier(TD);
+    return scopeModifier(TD, HB);
+  if (auto *OT = dyn_cast<ObjCObjectType>(T))
+    return scopeModifier(OT->getInterface(), HB);
   return llvm::None;
 }
 
@@ -466,11 +483,17 @@
 public:
   CollectExtraHighlightings(HighlightingsBuilder &H) : H(H) {}
 
+  bool IsFromDefaultLibrary(const NamedDecl *D) {
+    if (!D)
+      return false;
+    return H.InDefaultLibrary(D->getLocation());
+  }
+
   bool VisitDecltypeTypeLoc(DecltypeTypeLoc L) {
     if (auto K = kindForType(L.getTypePtr(), H.getResolver())) {
       auto &Tok = H.addToken(L.getBeginLoc(), *K)
                       .addModifier(HighlightingModifier::Deduced);
-      if (auto Mod = scopeModifier(L.getTypePtr()))
+      if (auto Mod = scopeModifier(L.getTypePtr(), H))
         Tok.addModifier(*Mod);
     }
     return true;
@@ -484,7 +507,7 @@
                              H.getResolver())) {
       auto &Tok = H.addToken(D->getTypeSpecStartLoc(), *K)
                       .addModifier(HighlightingModifier::Deduced);
-      if (auto Mod = scopeModifier(AT->getDeducedType().getTypePtrOrNull()))
+      if (auto Mod = scopeModifier(AT->getDeducedType().getTypePtrOrNull(), H))
         Tok.addModifier(*Mod);
     }
     return true;
@@ -493,7 +516,7 @@
   // We handle objective-C selectors specially, because one reference can
   // cover several non-contiguous tokens.
   void highlightObjCSelector(const ArrayRef<SourceLocation> &Locs, bool Decl,
-                             bool Class) {
+                             bool Class, bool DefaultLibrary) {
     HighlightingKind Kind =
         Class ? HighlightingKind::StaticMethod : HighlightingKind::Method;
     for (SourceLocation Part : Locs) {
@@ -503,20 +526,24 @@
         Tok.addModifier(HighlightingModifier::Declaration);
       if (Class)
         Tok.addModifier(HighlightingModifier::Static);
+      if (DefaultLibrary)
+        Tok.addModifier(HighlightingModifier::DefaultLibrary);
     }
   }
 
   bool VisitObjCMethodDecl(ObjCMethodDecl *OMD) {
     llvm::SmallVector<SourceLocation> Locs;
     OMD->getSelectorLocs(Locs);
-    highlightObjCSelector(Locs, /*Decl=*/true, OMD->isClassMethod());
+    highlightObjCSelector(Locs, /*Decl=*/true, OMD->isClassMethod(),
+                          IsFromDefaultLibrary(OMD));
     return true;
   }
 
   bool VisitObjCMessageExpr(ObjCMessageExpr *OME) {
     llvm::SmallVector<SourceLocation> Locs;
     OME->getSelectorLocs(Locs);
-    highlightObjCSelector(Locs, /*Decl=*/false, OME->isClassMessage());
+    highlightObjCSelector(Locs, /*Decl=*/false, OME->isClassMessage(),
+                          IsFromDefaultLibrary(OME->getMethodDecl()));
     return true;
   }
 
@@ -632,7 +659,7 @@
             if (auto *Templated = TD->getTemplatedDecl())
               Decl = Templated;
           }
-          if (auto Mod = scopeModifier(Decl))
+          if (auto Mod = scopeModifier(Decl, Builder))
             Tok.addModifier(*Mod);
           if (isConst(Decl))
             Tok.addModifier(HighlightingModifier::Readonly);
@@ -834,6 +861,8 @@
     return "fileScope"; // nonstandard
   case HighlightingModifier::GlobalScope:
     return "globalScope"; // nonstandard
+  case HighlightingModifier::DefaultLibrary:
+    return "defaultLibrary";
   }
   llvm_unreachable("unhandled HighlightingModifier");
 }
diff --git a/clang-tools-extra/clangd/test/initialize-params.test b/clang-tools-extra/clangd/test/initialize-params.test
--- a/clang-tools-extra/clangd/test/initialize-params.test
+++ b/clang-tools-extra/clangd/test/initialize-params.test
@@ -93,7 +93,8 @@
 # CHECK-NEXT:            "functionScope",
 # CHECK-NEXT:            "classScope",
 # CHECK-NEXT:            "fileScope",
-# CHECK-NEXT:            "globalScope"
+# CHECK-NEXT:            "globalScope",
+# CHECK-NEXT:            "defaultLibrary"
 # CHECK-NEXT:          ],
 # CHECK-NEXT:          "tokenTypes": [
 # CHECK-NEXT:            "variable",
diff --git a/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp b/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
--- a/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
@@ -69,13 +69,16 @@
                         std::vector<std::pair</*FileName*/ llvm::StringRef,
                                               /*FileContent*/ llvm::StringRef>>
                             AdditionalFiles = {},
-                        uint32_t ModifierMask = -1) {
+                        uint32_t ModifierMask = -1,
+                        std::vector<std::string> AdditionalArgs = {}) {
   Annotations Test(Code);
   TestTU TU;
   TU.Code = std::string(Test.code());
 
   TU.ExtraArgs.push_back("-std=c++20");
   TU.ExtraArgs.push_back("-xobjective-c++");
+  TU.ExtraArgs.insert(std::end(TU.ExtraArgs), std::begin(AdditionalArgs),
+                      std::end(AdditionalArgs));
 
   for (auto File : AdditionalFiles)
     TU.AdditionalFiles.insert({File.first, std::string(File.second)});
@@ -102,9 +105,9 @@
       struct {
       } $Variable_decl[[S]];
       void $Function_decl[[foo]](int $Parameter_decl[[A]], $Class[[AS]] $Parameter_decl[[As]]) {
-        $Primitive_deduced[[auto]] $LocalVariable_decl[[VeryLongVariableName]] = 12312;
+        $Primitive_deduced_defaultLibrary[[auto]] $LocalVariable_decl[[VeryLongVariableName]] = 12312;
         $Class[[AS]]     $LocalVariable_decl[[AA]];
-        $Primitive_deduced[[auto]] $LocalVariable_decl[[L]] = $LocalVariable[[AA]].$Field[[SomeMember]] + $Parameter[[A]];
+        $Primitive_deduced_defaultLibrary[[auto]] $LocalVariable_decl[[L]] = $LocalVariable[[AA]].$Field[[SomeMember]] + $Parameter[[A]];
         auto $LocalVariable_decl[[FN]] = [ $LocalVariable[[AA]]](int $Parameter_decl[[A]]) -> void {};
         $LocalVariable[[FN]](12312);
       }
@@ -320,8 +323,8 @@
       $Class_deduced[[decltype]](auto) $Variable_decl[[AF2]] = $Class[[Foo]]();
       $Class_deduced[[auto]] *$Variable_decl[[AFP]] = &$Variable[[AF]];
       $Enum_deduced[[auto]] &$Variable_decl[[AER]] = $Variable[[AE]];
-      $Primitive_deduced[[auto]] $Variable_decl[[Form]] = 10.2 + 2 * 4;
-      $Primitive_deduced[[decltype]]($Variable[[Form]]) $Variable_decl[[F]] = 10;
+      $Primitive_deduced_defaultLibrary[[auto]] $Variable_decl[[Form]] = 10.2 + 2 * 4;
+      $Primitive_deduced_defaultLibrary[[decltype]]($Variable[[Form]]) $Variable_decl[[F]] = 10;
       auto $Variable_decl[[Fun]] = []()->void{};
     )cpp",
       R"cpp(
@@ -731,6 +734,24 @@
     #define DEFINE_Y DEFINE(Y)
   )cpp"}},
                      ~ScopeModifierMask);
+
+  checkHighlightings(R"cpp(
+    #include "SYSObject.h"
+    @interface $Class_defaultLibrary[[SYSObject]] ($Namespace_decl[[UserCategory]])
+    @property(nonatomic, readonly) int $Field_decl_readonly[[user_property]];
+    @end
+    int $Function_decl[[somethingUsingSystemSymbols]]() {
+      $Class_defaultLibrary[[SYSObject]] *$LocalVariable_decl[[obj]] = [$Class_defaultLibrary[[SYSObject]] $StaticMethod_static_defaultLibrary[[new]]];
+      return $LocalVariable[[obj]].$Field_defaultLibrary[[value]] + $LocalVariable[[obj]].$Field_readonly[[user_property]];
+    }
+  )cpp",
+                     {{"SystemSDK/SYSObject.h", R"cpp(
+    @interface SYSObject
+    @property(nonatomic, assign) int value;
+    + (instancetype)new;
+    @end
+  )cpp"}},
+                     ~ScopeModifierMask, {"-isystemSystemSDK/"});
 }
 
 TEST(SemanticHighlighting, ScopeModifiers) {