diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -11509,6 +11509,42 @@
 public:
   BPFABIInfo(CodeGenTypes &CGT) : DefaultABIInfo(CGT) {}
 
+  ABIArgInfo classifyArgumentType(QualType Ty) const {
+    Ty = useFirstFieldIfTransparentUnion(Ty);
+
+    if (isAggregateTypeForABI(Ty)) {
+      uint64_t Bits = getContext().getTypeSize(Ty);
+      if (Bits == 0)
+        return ABIArgInfo::getIgnore();
+
+      // If the aggregate needs 1 or 2 registers, do not use reference.
+      if (Bits <= 128) {
+        llvm::Type *CoerceTy;
+        if (Bits <= 64) {
+          CoerceTy =
+              llvm::IntegerType::get(getVMContext(), llvm::alignTo(Bits, 8));
+        } else {
+          llvm::Type *RegTy = llvm::IntegerType::get(getVMContext(), 64);
+          CoerceTy = llvm::ArrayType::get(RegTy, 2);
+        }
+        return ABIArgInfo::getDirect(CoerceTy);
+      } else {
+        return getNaturalAlignIndirect(Ty);
+      }
+    }
+
+    if (const EnumType *EnumTy = Ty->getAs<EnumType>())
+      Ty = EnumTy->getDecl()->getIntegerType();
+
+    ASTContext &Context = getContext();
+    if (const auto *EIT = Ty->getAs<BitIntType>())
+      if (EIT->getNumBits() > Context.getTypeSize(Context.Int128Ty))
+        return getNaturalAlignIndirect(Ty);
+
+    return (isPromotableIntegerTypeForABI(Ty) ? ABIArgInfo::getExtend(Ty)
+                                              : ABIArgInfo::getDirect());
+  }
+
   ABIArgInfo classifyReturnType(QualType RetTy) const {
     if (RetTy->isVoidType())
       return ABIArgInfo::getIgnore();
diff --git a/clang/test/CodeGen/bpf-struct-argument.c b/clang/test/CodeGen/bpf-struct-argument.c
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGen/bpf-struct-argument.c
@@ -0,0 +1,36 @@
+// REQUIRES: bpf-registered-target
+// RUN: %clang_cc1 -triple bpf -O2 -emit-llvm -disable-llvm-passes %s -o - | FileCheck %s
+
+struct t1 {};
+struct t2 {
+  int a;
+};
+struct t3 {
+  int a;
+  long b;
+};
+struct t4 {
+  long a;
+  long b;
+  long c;
+};
+
+int foo1(struct t1 arg1, struct t2 arg2) {
+// CHECK: define dso_local i32 @foo1(i32 %arg2.coerce)
+  return arg2.a;
+}
+
+int foo2(struct t3 arg1, struct t4 arg2) {
+// CHECK: define dso_local i32 @foo2([2 x i64] %arg1.coerce, ptr noundef byval(%struct.t4) align 8 %arg2)
+  return arg1.a + arg2.a;
+}
+
+int foo3(void) {
+  struct t1 tmp1 = {};
+  struct t2 tmp2 = {};
+  struct t3 tmp3 = {};
+  struct t4 tmp4 = {};
+  return foo1(tmp1, tmp2) + foo2(tmp3, tmp4);
+// CHECK: call i32 @foo1(i32 %{{[a-zA-Z0-9]+}})
+// CHECK: call i32 @foo2([2 x i64] %{{[a-zA-Z0-9]+}}, ptr noundef byval(%struct.t4) align 8 %tmp4)
+}
diff --git a/clang/test/CodeGen/bpf-union-argument.c b/clang/test/CodeGen/bpf-union-argument.c
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGen/bpf-union-argument.c
@@ -0,0 +1,44 @@
+// REQUIRES: bpf-registered-target
+// RUN: %clang_cc1 -triple bpf -O2 -emit-llvm -disable-llvm-passes %s -o - | FileCheck %s
+
+union t1 {};
+union t2 {
+  int a;
+  long b;
+};
+union t3 {
+  struct {
+    int a;
+    long b;
+  };
+  long c;
+};
+union t4 {
+  struct {
+    long a;
+    long b;
+    long c;
+  };
+  long d;
+};
+
+int foo1(union t1 arg1, union t2 arg2) {
+// CHECK: define dso_local i32 @foo1(i64 %arg2.coerce)
+  return arg2.a;
+}
+
+int foo2(union t3 arg1, union t4 arg2) {
+// CHECK: define dso_local i32 @foo2([2 x i64] %arg1.coerce, ptr noundef byval(%union.t4) align 8 %arg2)
+  return arg1.a + arg2.a;
+
+}
+
+int foo3(void) {
+  union t1 tmp1 = {};
+  union t2 tmp2 = {};
+  union t3 tmp3 = {};
+  union t4 tmp4 = {};
+  return foo1(tmp1, tmp2) + foo2(tmp3, tmp4);
+// CHECK: call i32 @foo1(i64 %{{[a-zA-Z0-9]+}})
+// CHECK: call i32 @foo2([2 x i64] %{{[a-zA-Z0-9]+}}, ptr noundef byval(%union.t4) align 8 %tmp4)
+}