diff --git a/clang-tools-extra/clangd/InlayHints.cpp b/clang-tools-extra/clangd/InlayHints.cpp
--- a/clang-tools-extra/clangd/InlayHints.cpp
+++ b/clang-tools-extra/clangd/InlayHints.cpp
@@ -13,6 +13,7 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/RecursiveASTVisitor.h"
 #include "clang/Basic/SourceManager.h"
+#include "llvm/Support/raw_ostream.h"
 
 namespace clang {
 namespace clangd {
@@ -314,6 +315,10 @@
         toHalfOpenFileRange(AST.getSourceManager(), AST.getLangOpts(), R);
     if (!FileRange)
       return;
+    // The hint may be in a file other than the main file (for example, a header
+    // file that was included after the preamble), do not show in that case.
+    if (!AST.getSourceManager().isWrittenInMainFile(FileRange->getBegin()))
+      return;
     Results.push_back(InlayHint{
         Range{
             sourceLocToPosition(AST.getSourceManager(), FileRange->getBegin()),
diff --git a/clang-tools-extra/clangd/unittests/InlayHintTests.cpp b/clang-tools-extra/clangd/unittests/InlayHintTests.cpp
--- a/clang-tools-extra/clangd/unittests/InlayHintTests.cpp
+++ b/clang-tools-extra/clangd/unittests/InlayHintTests.cpp
@@ -9,6 +9,7 @@
 #include "InlayHints.h"
 #include "Protocol.h"
 #include "TestTU.h"
+#include "TestWorkspace.h"
 #include "XRefs.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
@@ -398,6 +399,28 @@
                        ExpectedHint{"timeout_millis: ", "timeout_millis"});
 }
 
+TEST(ParameterHints, IncludeAtNonGlobalScope) {
+  Annotations FooInc(R"cpp(
+    void bar() { foo(42); }
+  )cpp");
+  Annotations FooCC(R"cpp(
+    struct S {
+      void foo(int param);
+      #include "foo.inc"
+    };
+  )cpp");
+
+  TestWorkspace Workspace;
+  Workspace.addSource("foo.inc", FooInc.code());
+  Workspace.addMainFile("foo.cc", FooCC.code());
+
+  auto AST = Workspace.openFile("foo.cc");
+  ASSERT_TRUE(bool(AST));
+
+  // Ensure the hint for the call in foo.inc is NOT materialized in foo.cc.
+  EXPECT_EQ(hintsOfKind(*AST, InlayHintKind::ParameterHint).size(), 0u);
+}
+
 TEST(TypeHints, Smoke) {
   assertTypeHints(R"cpp(
     auto $waldo[[waldo]] = 42;