diff --git a/clang/include/clang/AST/ASTImporterLookupTable.h b/clang/include/clang/AST/ASTImporterLookupTable.h
--- a/clang/include/clang/AST/ASTImporterLookupTable.h
+++ b/clang/include/clang/AST/ASTImporterLookupTable.h
@@ -63,8 +63,24 @@
   ASTImporterLookupTable(TranslationUnitDecl &TU);
   void add(NamedDecl *ND);
   void remove(NamedDecl *ND);
+  // Sometimes a declaration is created first with a temporarily value of decl
+  // context (often the translation unit) and later moved to the final context.
+  // This happens for declarations that are created before the final declaration
+  // context. In such cases the lookup table needs to be updated.
+  // (The declaration is in these cases not added to the temporary decl context,
+  // only its parent is set.)
+  // FIXME: It would be better to not add the declaration to the temporary
+  // context at all in the lookup table, but this requires big change in
+  // ASTImporter.
+  // The function should be called when the old context is definitely different
+  // from the new.
+  void update(NamedDecl *ND, DeclContext *OldDC);
   using LookupResult = DeclList;
   LookupResult lookup(DeclContext *DC, DeclarationName Name) const;
+  // Check if the `ND` is within the lookup table (with its current name) in
+  // context `DC`. This is intended for debug purposes when the DeclContext of a
+  // NamedDecl is changed.
+  bool contains(DeclContext *DC, NamedDecl *ND) const;
   void dump(DeclContext *DC) const;
   void dump() const;
 };
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -3503,6 +3503,8 @@
   for (auto *Param : Parameters) {
     Param->setOwningFunction(ToFunction);
     ToFunction->addDeclInternal(Param);
+    if (ASTImporterLookupTable *LT = Importer.SharedState->getLookupTable())
+      LT->update(Param, Importer.getToContext().getTranslationUnitDecl());
   }
   ToFunction->setParams(Parameters);
 
diff --git a/clang/lib/AST/ASTImporterLookupTable.cpp b/clang/lib/AST/ASTImporterLookupTable.cpp
--- a/clang/lib/AST/ASTImporterLookupTable.cpp
+++ b/clang/lib/AST/ASTImporterLookupTable.cpp
@@ -117,6 +117,19 @@
     remove(ReDC, ND);
 }
 
+void ASTImporterLookupTable::update(NamedDecl *ND, DeclContext *OldDC) {
+  assert(OldDC != ND->getDeclContext() &&
+         "DeclContext should be changed before update");
+  if (contains(ND->getDeclContext(), ND)) {
+    assert(!contains(OldDC, ND) &&
+           "Decl should not be found in the old context if already in the new");
+    return;
+  }
+
+  remove(OldDC, ND);
+  add(ND);
+}
+
 ASTImporterLookupTable::LookupResult
 ASTImporterLookupTable::lookup(DeclContext *DC, DeclarationName Name) const {
   auto DCI = LookupTable.find(DC->getPrimaryContext());
@@ -131,6 +144,10 @@
   return NamesI->second;
 }
 
+bool ASTImporterLookupTable::contains(DeclContext *DC, NamedDecl *ND) const {
+  return 0 < lookup(DC, ND->getDeclName()).count(ND);
+}
+
 void ASTImporterLookupTable::dump(DeclContext *DC) const {
   auto DCI = LookupTable.find(DC->getPrimaryContext());
   if (DCI == LookupTable.end())
diff --git a/clang/unittests/AST/ASTImporterTest.cpp b/clang/unittests/AST/ASTImporterTest.cpp
--- a/clang/unittests/AST/ASTImporterTest.cpp
+++ b/clang/unittests/AST/ASTImporterTest.cpp
@@ -5375,6 +5375,33 @@
   CheckError(FromFooC);
 }
 
+TEST_P(ErrorHandlingTest, ODRViolationWithinParmVarDecls) {
+  // Importing of 'f' and parameter 'P' should cause an ODR error.
+  // The error happens after the ParmVarDecl for 'P' was already created.
+  // This is a special case because the ParmVarDecl has a temporary DeclContext.
+  // Expected is no crash at error handling of ASTImporter.
+  constexpr auto ToTUCode = R"(
+      struct X {
+        char A;
+      };
+      )";
+  constexpr auto FromTUCode = R"(
+      struct X {
+        enum Y { Z };
+      };
+      void f(int P = X::Z);
+      )";
+  Decl *ToTU = getToTuDecl(ToTUCode, Lang_CXX11);
+  static_cast<void>(ToTU);
+  Decl *FromTU = getTuDecl(FromTUCode, Lang_CXX11);
+  auto *FromF = FirstDeclMatcher<FunctionDecl>().match(
+      FromTU, functionDecl(hasName("f")));
+  ASSERT_TRUE(FromF);
+
+  auto *ImportedF = Import(FromF, Lang_CXX11);
+  EXPECT_FALSE(ImportedF);
+}
+
 TEST_P(ASTImporterOptionSpecificTestBase, LambdaInFunctionBody) {
   Decl *FromTU = getTuDecl(
       R"(
@@ -6192,6 +6219,21 @@
   ASSERT_TRUE(ToD);
 }
 
+TEST_P(ImportFunctions, ParmVarDeclDeclContext) {
+  constexpr auto FromTUCode = R"(
+      void f(int P);
+      )";
+  Decl *FromTU = getTuDecl(FromTUCode, Lang_CXX11);
+  auto *FromF = FirstDeclMatcher<FunctionDecl>().match(
+      FromTU, functionDecl(hasName("f")));
+  ASSERT_TRUE(FromF);
+
+  auto *ImportedF = Import(FromF, Lang_CXX11);
+  EXPECT_TRUE(ImportedF);
+  EXPECT_TRUE(SharedStatePtr->getLookupTable()->contains(
+      ImportedF, ImportedF->getParamDecl(0)));
+}
+
 // FIXME Move these tests out of ASTImporterTest. For that we need to factor
 // out the ASTImporter specific pars from ASTImporterOptionSpecificTestBase
 // into a new test Fixture. Then we should lift up this Fixture to its own