diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -11696,7 +11696,7 @@
                                                 const Decl *D, GVALinkage L) {
   // See http://msdn.microsoft.com/en-us/library/xa0d9ste.aspx
   // dllexport/dllimport on inline functions.
-  if (D->hasAttr<DLLImportAttr>()) {
+  if (D->hasAttr<DLLImportAttr>() && !D->hasAttr<ExcludeFromExplicitInstantiationAttr>()) {
     if (L == GVA_DiscardableODR || L == GVA_StrongODR)
       return GVA_AvailableExternally;
   } else if (D->hasAttr<DLLExportAttr>()) {
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1512,7 +1512,7 @@
 
 void CodeGenModule::setDLLImportDLLExport(llvm::GlobalValue *GV,
                                           const NamedDecl *D) const {
-  if (D && D->isExternallyVisible()) {
+  if (D && D->isExternallyVisible() && !D->hasAttr<ExcludeFromExplicitInstantiationAttr>()) {
     if (D->hasAttr<DLLImportAttr>())
       GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
     else if ((D->hasAttr<DLLExportAttr>() ||
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -818,10 +818,13 @@
     if (isa<CXXDeductionGuideDecl>(ND))
       continue;
 
-    if (ND->hasAttr<DLLImportAttr>() || ND->hasAttr<DLLExportAttr>()) {
+    if ((ND->hasAttr<DLLImportAttr>() || ND->hasAttr<DLLExportAttr>()) &&
+        !ND->hasAttr<ExcludeFromExplicitInstantiationAttr>()) {
       // An exported function will always be emitted when defined, so even if
       // the function is inline, it doesn't have to be emitted in this TU. An
-      // imported function implies that it has been exported somewhere else.
+      // imported function implies that it has been exported somewhere else,
+      // except if it is marked with exclude_from_explicit_instantiation, in
+      // which case there might not be a definition elsewhere.
       continue;
     }
 
diff --git a/clang/test/CodeGenCXX/attr-exclude_from_explicit_instantiation.dllimport.cpp b/clang/test/CodeGenCXX/attr-exclude_from_explicit_instantiation.dllimport.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGenCXX/attr-exclude_from_explicit_instantiation.dllimport.cpp
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-windows -fms-extensions -emit-llvm -O0 -o - %s | FileCheck %s
+
+// Test that dllimport and exclude_from_explicit_instantiation work properly
+// together. Specifically, we check that when exclude_from_explicit_instantiation
+// is used on a method, the compiler doesn't expect it to be provided externally
+// even if it is marked with dllimport.
+//
+// https://github.com/llvm/llvm-project/issues/40363
+
+#define DLLIMPORT __declspec(dllimport)
+#define EXCLUDE_FROM_EXPLICIT_INSTANTIATION __attribute__((exclude_from_explicit_instantiation))
+
+template <class T>
+struct DLLIMPORT Foo {
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void x() {}
+};
+
+template <class T>
+struct Bar {
+  DLLIMPORT EXCLUDE_FROM_EXPLICIT_INSTANTIATION void x() {}
+};
+
+extern template struct Foo<int>;
+extern template struct Bar<int>;
+
+void test(Foo<int>& foo, Bar<int>& bar) {
+  // CHECK-DAG: define linkonce_odr dso_local void @"?x@?$Foo@H@@QEAAXXZ"
+  foo.x();
+
+  // CHECK-DAG: define linkonce_odr dso_local void @"?x@?$Bar@H@@QEAAXXZ"
+  bar.x();
+}
diff --git a/clang/test/SemaCXX/attr-exclude_from_explicit_instantiation.dllimport.cpp b/clang/test/SemaCXX/attr-exclude_from_explicit_instantiation.dllimport.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaCXX/attr-exclude_from_explicit_instantiation.dllimport.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-windows -fms-extensions -verify %s
+
+// Test that an entity marked as both dllimport and exclude_from_explicit_instantiation
+// isn't instantiated.
+
+#define DLLIMPORT __declspec(dllimport)
+#define EXCLUDE_FROM_EXPLICIT_INSTANTIATION __attribute__((exclude_from_explicit_instantiation))
+
+template <class T>
+struct DLLIMPORT Foo {
+  EXCLUDE_FROM_EXPLICIT_INSTANTIATION void x();
+};
+
+template <class T>
+struct Bar {
+  DLLIMPORT EXCLUDE_FROM_EXPLICIT_INSTANTIATION inline void x();
+};
+
+template <class T>
+void Foo<T>::x() { using Fail = typename T::fail; }
+
+template <class T>
+DLLIMPORT inline void Bar<T>::x() { using Fail = typename T::fail; }
+
+// expected-no-diagnostics
+template struct Foo<int>;
+template struct Bar<int>;