diff --git a/toolchain/check/cpp/export.cpp b/toolchain/check/cpp/export.cpp
index a5e2bea73213..192a36d54b62 100644
--- a/toolchain/check/cpp/export.cpp
+++ b/toolchain/check/cpp/export.cpp
@@ -1254,9 +1254,24 @@ static auto BuildCppToCarbonThunkBody(Context& context,
     stmts.push_back(call.get());
 
     if (has_return_value) {
-      auto* return_stmt = clang::ReturnStmt::Create(
-          sema.getASTContext(), clang_loc, return_storage_expr.get(),
-          return_storage_var_decl);
+      // Return `return_storage` by value. The variable is an NRVO candidate,
+      // so CodeGen constructs it directly in the return slot and ignores the
+      // returned expression, but the AST should still model a by-value return
+      // (a prvalue) rather than returning an lvalue referring to the local.
+      clang::QualType return_type = return_storage_var_decl->getType();
+      clang::Expr* return_val_expr = sema.BuildDeclRefExpr(
+          return_storage_var_decl, return_type, clang::VK_LValue, clang_loc);
+      // TODO: Lvalue-to-rvalue conversion isn't valid for class types. Those
+      // would need a (elided) copy/move construction, which may not exist.
+      if (!return_type->getAsCXXRecordDecl() && !return_type->isNullPtrType()) {
+        return_val_expr = clang::ImplicitCastExpr::Create(
+            sema.getASTContext(), return_type, clang::CK_LValueToRValue,
+            return_val_expr, /*BasePath=*/nullptr, clang::VK_PRValue,
+            clang::FPOptionsOverride());
+      }
+      auto* return_stmt =
+          clang::ReturnStmt::Create(sema.getASTContext(), clang_loc,
+                                    return_val_expr, return_storage_var_decl);
       stmts.push_back(return_stmt);
     }
   }
diff --git a/toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon b/toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon
index 0e77bb335775..9ed7ad38d3ff 100644
--- a/toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/export/thunk_ast.carbon
@@ -35,20 +35,21 @@ fn F(i: i32) -> i32 {
 // CHECK:STDOUT: |   | | `-ImplicitCastExpr {{0x[a-f0-9]+}} <col:21> 'const int' lvalue <NoOp>
 // CHECK:STDOUT: |   | |   `-DeclRefExpr {{0x[a-f0-9]+}} <col:21> 'int' lvalue Var {{0x[a-f0-9]+}} 'return_storage' 'int'
 // CHECK:STDOUT: |   | `-ReturnStmt {{0x[a-f0-9]+}} <col:21> nrvo_candidate(Var {{0x[a-f0-9]+}} 'return_storage' 'int')
-// CHECK:STDOUT: |   |   `-DeclRefExpr {{0x[a-f0-9]+}} <col:21> 'int' lvalue Var {{0x[a-f0-9]+}} 'return_storage' 'int'
+// CHECK:STDOUT: |   |   `-ImplicitCastExpr {{0x[a-f0-9]+}} <col:21> 'int' <LValueToRValue>
+// CHECK:STDOUT: |   |     `-DeclRefExpr {{0x[a-f0-9]+}} <col:21> 'int' lvalue Var {{0x[a-f0-9]+}} 'return_storage' 'int'
 // CHECK:STDOUT: |   |-AlwaysInlineAttr {{0x[a-f0-9]+}} <<invalid sloc>> Implicit always_inline
 // CHECK:STDOUT: |   `-InternalLinkageAttr {{0x[a-f0-9]+}} <<invalid sloc>> Implicit
-// CHECK:STDOUT: |-FunctionDecl {{0x[a-f0-9]+}} <line:38:1, line:40:1> line:38:5 in thunk_with_args_and_return.carbon hidden G 'int (int)' external-linkage
+// CHECK:STDOUT: |-FunctionDecl {{0x[a-f0-9]+}} <line:39:1, line:41:1> line:39:5 in thunk_with_args_and_return.carbon hidden G 'int (int)' external-linkage
 // CHECK:STDOUT: | |-ParmVarDecl {{0x[a-f0-9]+}} <col:7, col:11> col:11 in thunk_with_args_and_return.carbon hidden used i 'int'
-// CHECK:STDOUT: | `-CompoundStmt {{0x[a-f0-9]+}} <col:14, line:40:1>
-// CHECK:STDOUT: |   `-ReturnStmt {{0x[a-f0-9]+}} <line:39:3, col:21>
+// CHECK:STDOUT: | `-CompoundStmt {{0x[a-f0-9]+}} <col:14, line:41:1>
+// CHECK:STDOUT: |   `-ReturnStmt {{0x[a-f0-9]+}} <line:40:3, col:21>
 // CHECK:STDOUT: |     `-CallExpr {{0x[a-f0-9]+}} <col:10, col:21> 'int'
 // CHECK:STDOUT: |       |-ImplicitCastExpr {{0x[a-f0-9]+}} <col:10, col:18> 'int (*)(int)' <FunctionToPointerDecay>
 // CHECK:STDOUT: |       | `-DeclRefExpr {{0x[a-f0-9]+}} <col:10, col:18> 'int (int)' lvalue Function {{0x[a-f0-9]+}} 'F' 'int (int)'
 // CHECK:STDOUT: |       |   `-NestedNameSpecifier Namespace {{0x[a-f0-9]+}} 'Carbon'
 // CHECK:STDOUT: |       `-ImplicitCastExpr {{0x[a-f0-9]+}} <col:20> 'int' <LValueToRValue>
 // CHECK:STDOUT: |         `-DeclRefExpr {{0x[a-f0-9]+}} <col:20> 'int' lvalue ParmVar {{0x[a-f0-9]+}} 'i' 'int'
-// CHECK:STDOUT: `-ImportDecl {{0x[a-f0-9]+}} <line:41:4> col:4 in thunk_with_args_and_return.carbon implicit thunk_with_args_and_return.carbon
+// CHECK:STDOUT: `-ImportDecl {{0x[a-f0-9]+}} <line:42:4> col:4 in thunk_with_args_and_return.carbon implicit thunk_with_args_and_return.carbon
   return i;
 }