diff --git a/src/arch/riscv64/CodeGen.zig b/src/arch/riscv64/CodeGen.zig
index f887c6cb13..0c6da840eb 100644
--- a/src/arch/riscv64/CodeGen.zig
+++ b/src/arch/riscv64/CodeGen.zig
@@ -3364,8 +3364,38 @@ fn airOptionalPayloadPtr(func: *Func, inst: Air.Inst.Index) !void {
 }
 
 fn airOptionalPayloadPtrSet(func: *Func, inst: Air.Inst.Index) !void {
+    const zcu = func.pt.zcu;
+
     const ty_op = func.air.instructions.items(.data)[@intFromEnum(inst)].ty_op;
-    const result: MCValue = if (func.liveness.isUnused(inst)) .unreach else return func.fail("TODO implement .optional_payload_ptr_set for {}", .{func.target.cpu.arch});
+    const result: MCValue = if (func.liveness.isUnused(inst)) .unreach else result: {
+        const dst_ty = func.typeOfIndex(inst);
+        const src_ty = func.typeOf(ty_op.operand);
+        const opt_ty = src_ty.childType(zcu);
+        const src_mcv = try func.resolveInst(ty_op.operand);
+
+        if (opt_ty.optionalReprIsPayload(zcu)) {
+            break :result if (func.reuseOperand(inst, ty_op.operand, 0, src_mcv))
+                src_mcv
+            else
+                try func.copyToNewRegister(inst, src_mcv);
+        }
+
+        const dst_mcv: MCValue = if (src_mcv.isRegister() and
+            func.reuseOperand(inst, ty_op.operand, 0, src_mcv))
+            src_mcv
+        else
+            try func.copyToNewRegister(inst, src_mcv);
+
+        const pl_ty = dst_ty.childType(zcu);
+        const pl_abi_size: i32 = @intCast(pl_ty.abiSize(zcu));
+        try func.genSetMem(
+            .{ .reg = dst_mcv.getReg().? },
+            pl_abi_size,
+            Type.bool,
+            .{ .immediate = 1 },
+        );
+        break :result dst_mcv;
+    };
     return func.finishAir(inst, result, .{ ty_op.operand, .none, .none });
 }
 
diff --git a/test/behavior/cast.zig b/test/behavior/cast.zig
index b414977ad6..7dca19d212 100644
--- a/test/behavior/cast.zig
+++ b/test/behavior/cast.zig
@@ -1875,7 +1875,6 @@ test "peer type resolution: vector and optional vector" {
     if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; // TODO
-    if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest;
 
     var a: ?@Vector(3, u32) = .{ 0, 1, 2 };
     var b: @Vector(3, u32) = .{ 3, 4, 5 };
diff --git a/test/behavior/decl_literals.zig b/test/behavior/decl_literals.zig
index b5961c2c13..f2f7f8a81f 100644
--- a/test/behavior/decl_literals.zig
+++ b/test/behavior/decl_literals.zig
@@ -33,8 +33,7 @@ test "decl literal with pointer" {
 }
 
 test "call decl literal with optional" {
-    if (builtin.zig_backend == .stage2_riscv64 or
-        builtin.zig_backend == .stage2_sparc64 or
+    if (builtin.zig_backend == .stage2_sparc64 or
         builtin.zig_backend == .stage2_arm or
         builtin.zig_backend == .stage2_aarch64 or
         builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest; // TODO
diff --git a/test/behavior/optional.zig b/test/behavior/optional.zig
index 53738a107b..967bc8cf85 100644
--- a/test/behavior/optional.zig
+++ b/test/behavior/optional.zig
@@ -320,7 +320,6 @@ test "coerce an anon struct literal to optional struct" {
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
-    if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest;
 
     const S = struct {
         const Struct = struct {
diff --git a/test/behavior/struct.zig b/test/behavior/struct.zig
index 4694758e19..989da34ae7 100644
--- a/test/behavior/struct.zig
+++ b/test/behavior/struct.zig
@@ -1165,7 +1165,6 @@ test "anon init through error unions and optionals" {
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
-    if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest;
 
     const S = struct {
         a: u32,
@@ -1193,7 +1192,6 @@ test "anon init through optional" {
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
-    if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest;
 
     const S = struct {
         a: u32,
@@ -1503,7 +1501,6 @@ test "no dependency loop on pointer to optional struct" {
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
-    if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest;
 
     const S = struct {
         const A = struct { b: B };
diff --git a/test/behavior/union.zig b/test/behavior/union.zig
index 9938c3c045..b0209c124e 100644
--- a/test/behavior/union.zig
+++ b/test/behavior/union.zig
@@ -1268,7 +1268,6 @@ test "extern union most-aligned field is smaller" {
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
-    if (builtin.zig_backend == .stage2_riscv64) return error.SkipZigTest;
 
     const U = extern union {
         in6: extern struct {