diff --git a/clang/lib/CodeGen/Targets/RISCV.cpp b/clang/lib/CodeGen/Targets/RISCV.cpp
index e3232b61a693c..5bf0f29903f56 100644
--- a/clang/lib/CodeGen/Targets/RISCV.cpp
+++ b/clang/lib/CodeGen/Targets/RISCV.cpp
@@ -609,6 +609,10 @@ ABIArgInfo RISCVABIInfo::classifyArgumentType(QualType Ty, bool IsFixed,
   if (isEmptyRecord(getContext(), Ty, true) && Size == 0)
     return ABIArgInfo::getIgnore();
 
+  // Structures with flexible arrays are always indirect.
+  if (Ty->isStructureTypeWithFlexibleArrayMember())
+    return getNaturalAlignIndirect(Ty, /*ByVal=*/false);
+
   // Pass floating point values via FPRs if possible.
   if (IsFixed && Ty->isFloatingType() && !Ty->isComplexType() &&
       FLen >= Size && ArgFPRsLeft) {
diff --git a/clang/test/CodeGen/RISCV/abi-flexible-array-members.cpp b/clang/test/CodeGen/RISCV/abi-flexible-array-members.cpp
new file mode 100644
index 0000000000000..b6f25982fd3f6
--- /dev/null
+++ b/clang/test/CodeGen/RISCV/abi-flexible-array-members.cpp
@@ -0,0 +1,46 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --filter "^define |^entry:" --version 2
+// RUN: %clang_cc1 -x c++ -triple riscv32 -target-feature +f -target-abi ilp32f -emit-llvm %s -o - \
+// RUN:   | FileCheck -check-prefixes=CHECK32 %s
+// RUN: %clang_cc1 -x c++ -triple riscv32 -target-feature +f -target-feature +d -target-abi ilp32d -emit-llvm %s -o - \
+// RUN:   | FileCheck -check-prefixes=CHECK32 %s
+// RUN: %clang_cc1 -x c++ -triple riscv64 -target-feature +f -target-abi lp64f -emit-llvm %s -o - \
+// RUN:   | FileCheck -check-prefixes=CHECK64 %s
+// RUN: %clang_cc1 -x c++ -triple riscv64 -target-feature +f -target-feature +d -target-abi lp64d -emit-llvm %s -o - \
+// RUN:   | FileCheck -check-prefixes=CHECK64 %s
+
+#include <stdint.h>
+
+// Structs containing C99 flexible array members should always be passed and returned on the stack.
+
+struct s1 {
+    int a;
+    int b[];
+};
+
+// CHECK32-LABEL: define dso_local void @_Z7test_012s1
+// CHECK32-SAME: (ptr dead_on_unwind noalias writable sret([[STRUCT_S1:%.*]]) align 4 [[AGG_RESULT:%.*]], ptr noundef byval([[STRUCT_S1]]) align 4 [[A:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK32:  entry:
+//
+// CHECK64-LABEL: define dso_local void @_Z7test_012s1
+// CHECK64-SAME: (ptr dead_on_unwind noalias writable sret([[STRUCT_S1:%.*]]) align 4 [[AGG_RESULT:%.*]], ptr noundef byval([[STRUCT_S1]]) align 4 [[A:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK64:  entry:
+//
+struct s1 test_01(struct s1 a) {
+  return a;
+}
+
+
+// CHECK32-LABEL: define dso_local void @_Z7test_02v
+// CHECK32-SAME: (ptr dead_on_unwind noalias writable sret([[STRUCT_S1:%.*]]) align 4 [[AGG_RESULT:%.*]]) #[[ATTR0]] {
+// CHECK32:  entry:
+//
+// CHECK64-LABEL: define dso_local void @_Z7test_02v
+// CHECK64-SAME: (ptr dead_on_unwind noalias writable sret([[STRUCT_S1:%.*]]) align 4 [[AGG_RESULT:%.*]]) #[[ATTR0]] {
+// CHECK64:  entry:
+//
+struct s1 test_02() {
+    struct s1 r;
+    r.a = 0;
+    r.b[0] = 1;
+    return r;
+}