diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index d04e1c781b4e2..86f64bf2a2425 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -281,11 +281,18 @@ bool clang::CanElideDeclDef(const Decl *D) {
 
     if (FD->isDependentContext())
       return false;
+
+    if (FD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
+      return false;
   }
 
   if (auto *VD = dyn_cast<VarDecl>(D)) {
     if (!VD->getDeclContext()->getRedeclContext()->isFileContext() ||
-        VD->isInline() || VD->isConstexpr() || isa<ParmVarDecl>(VD))
+        VD->isInline() || VD->isConstexpr() || isa<ParmVarDecl>(VD) ||
+        // Constant initialized variable may not affect the ABI, but they
+        // may be used in constant evaluation in the frontend, so we have
+        // to remain them.
+        VD->hasConstantInitialization())
       return false;
 
     if (VD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
diff --git a/clang/test/Modules/reduced-bmi-generating-codes.cppm b/clang/test/Modules/reduced-bmi-generating-codes.cppm
new file mode 100644
index 0000000000000..13dcda06437b2
--- /dev/null
+++ b/clang/test/Modules/reduced-bmi-generating-codes.cppm
@@ -0,0 +1,40 @@
+// Although the reduced BMI are not designed to be generated,
+// it is helpful for testing whether we've reduced the definitions.
+//
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 -triple %itanium_abi_triple %t/a.cppm \
+// RUN:     -emit-reduced-module-interface -o %t/a.pcm
+// RUN: %clang_cc1 -std=c++20 -triple %itanium_abi_triple %t/b.cpp \
+// RUN:     -fmodule-file=a=%t/a.pcm -S -emit-llvm -o - \
+// RUN:     | FileCheck %t/b.cpp
+
+//--- a.cppm
+export module a;
+
+export template <class T>
+class A {
+public:
+    int member() {
+        return 43;
+    }
+};
+
+// Instantiate `A<int>::member()`.
+export int a_member = A<int>().member();
+
+export const int a = 43;
+
+//--- b.cpp
+import a;
+
+static_assert(a == 43);
+
+int b() {
+    A<int> a;
+    return a.member();
+}
+
+// CHECK: define{{.*}}@_ZNW1a1AIiE6memberEv