diff --git a/flang/lib/Optimizer/CodeGen/Target.cpp b/flang/lib/Optimizer/CodeGen/Target.cpp
index 6c148dffb0e55..5f746bf80e9d5 100644
--- a/flang/lib/Optimizer/CodeGen/Target.cpp
+++ b/flang/lib/Optimizer/CodeGen/Target.cpp
@@ -1091,6 +1091,13 @@ struct TargetLoongArch64 : public GenericTarget<TargetLoongArch64> {
       // Two distinct element type arguments (re, im)
       marshal.emplace_back(eleTy, AT{});
       marshal.emplace_back(eleTy, AT{});
+    } else if (sem == &llvm::APFloat::IEEEquad()) {
+      // Use a type that will be translated into LLVM as:
+      // { fp128, fp128 }   struct of 2 fp128, byval
+      marshal.emplace_back(
+          fir::ReferenceType::get(mlir::TupleType::get(
+              eleTy.getContext(), mlir::TypeRange{eleTy, eleTy})),
+          AT{/*align=*/16, /*byval=*/true});
     } else {
       typeTodo(sem, loc, "argument");
     }
@@ -1108,6 +1115,13 @@ struct TargetLoongArch64 : public GenericTarget<TargetLoongArch64> {
       marshal.emplace_back(mlir::TupleType::get(eleTy.getContext(),
                                                 mlir::TypeRange{eleTy, eleTy}),
                            AT{/*alignment=*/0, /*byval=*/true});
+    } else if (sem == &llvm::APFloat::IEEEquad()) {
+      // Use a type that will be translated into LLVM as:
+      // { fp128, fp128 }   struct of 2 fp128, sret, align 16
+      marshal.emplace_back(
+          fir::ReferenceType::get(mlir::TupleType::get(
+              eleTy.getContext(), mlir::TypeRange{eleTy, eleTy})),
+          AT{/*align=*/16, /*byval=*/false, /*sret=*/true});
     } else {
       typeTodo(sem, loc, "return");
     }
diff --git a/flang/test/Fir/target-rewrite-complex16.fir b/flang/test/Fir/target-rewrite-complex16.fir
index 4f807e828d8f1..86a5b0051ab2e 100644
--- a/flang/test/Fir/target-rewrite-complex16.fir
+++ b/flang/test/Fir/target-rewrite-complex16.fir
@@ -1,4 +1,5 @@
 // RUN: fir-opt --target-rewrite="target=x86_64-unknown-linux-gnu" %s | FileCheck %s
+// RUN: fir-opt --target-rewrite="target=loongarch64-unknown-linux-gnu" %s | FileCheck %s
 
 // Test that we rewrite the signature and body of a func.function that returns a
 // complex<16>.