diff --git a/clang-tools-extra/clangd/FindTarget.cpp b/clang-tools-extra/clangd/FindTarget.cpp
--- a/clang-tools-extra/clangd/FindTarget.cpp
+++ b/clang-tools-extra/clangd/FindTarget.cpp
@@ -194,6 +194,9 @@
         for (auto *D : OE->decls())
           Outer.add(D, Flags);
       }
+      void VisitSizeOfPackExpr(const SizeOfPackExpr *SE) {
+        Outer.add(SE->getPack(), Flags);
+      }
       void VisitCXXConstructExpr(const CXXConstructExpr *CCE) {
         Outer.add(CCE->getConstructor(), Flags);
       }
@@ -491,6 +494,13 @@
                                   llvm::SmallVector<const NamedDecl *, 1>(
                                       E->decls().begin(), E->decls().end())});
     }
+
+    void VisitSizeOfPackExpr(const SizeOfPackExpr *E) {
+      Refs.push_back(ReferenceLoc{NestedNameSpecifierLoc(),
+                                  E->getPackLoc(),
+                                  /*IsDecl=*/false,
+                                  {E->getPack()}});
+    }
   };
 
   Visitor V;
diff --git a/clang-tools-extra/clangd/unittests/FindTargetTests.cpp b/clang-tools-extra/clangd/unittests/FindTargetTests.cpp
--- a/clang-tools-extra/clangd/unittests/FindTargetTests.cpp
+++ b/clang-tools-extra/clangd/unittests/FindTargetTests.cpp
@@ -260,6 +260,15 @@
   )cpp";
   // FIXME: deduced type missing in AST. https://llvm.org/PR42914
   EXPECT_DECLS("AutoTypeLoc");
+
+  Code = R"cpp(
+    template <typename... E>
+    struct S {
+      static const int size = sizeof...([[E]]);
+    };
+  )cpp";
+  // FIXME: We don't do a good job printing TemplateTypeParmDecls, apparently!
+  EXPECT_DECLS("SizeOfPackExpr", "");
 }
 
 TEST_F(TargetDeclTest, ClassTemplate) {
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
@@ -625,6 +625,13 @@
 $InactiveCode[[]]      #else
       int $Variable[[Active2]];
       #endif
+    )cpp",
+      // Argument to 'sizeof...'
+      R"cpp(
+      template <typename... $TemplateParameter[[Elements]]>
+      struct $Class[[TupleSize]] {
+        static const int $StaticField[[size]] = sizeof...($TemplateParameter[[Elements]]);
+      };
     )cpp"};
   for (const auto &TestCase : TestCases) {
     checkHighlightings(TestCase);