diff --git a/cranelift/codegen/src/isa/aarch64/lower_inst.rs b/cranelift/codegen/src/isa/aarch64/lower_inst.rs
index 5fe62da697..819071cc96 100644
--- a/cranelift/codegen/src/isa/aarch64/lower_inst.rs
+++ b/cranelift/codegen/src/isa/aarch64/lower_inst.rs
@@ -2157,12 +2157,12 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
             let out_bits = ty_bits(ctx.output_ty(insn, 0));
             let signed = op == Opcode::FcvtToSint;
             let op = match (signed, in_bits, out_bits) {
-                (false, 32, 32) => FpuToIntOp::F32ToU32,
-                (true, 32, 32) => FpuToIntOp::F32ToI32,
+                (false, 32, 8) | (false, 32, 16) | (false, 32, 32) => FpuToIntOp::F32ToU32,
+                (true, 32, 8) | (true, 32, 16) | (true, 32, 32) => FpuToIntOp::F32ToI32,
                 (false, 32, 64) => FpuToIntOp::F32ToU64,
                 (true, 32, 64) => FpuToIntOp::F32ToI64,
-                (false, 64, 32) => FpuToIntOp::F64ToU32,
-                (true, 64, 32) => FpuToIntOp::F64ToI32,
+                (false, 64, 8) | (false, 64, 16) | (false, 64, 32) => FpuToIntOp::F64ToU32,
+                (true, 64, 8) | (true, 64, 16) | (true, 64, 32) => FpuToIntOp::F64ToI32,
                 (false, 64, 64) => FpuToIntOp::F64ToU64,
                 (true, 64, 64) => FpuToIntOp::F64ToI64,
                 _ => panic!("Unknown input/output-bits combination"),
@@ -2199,6 +2199,16 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
             if in_bits == 32 {
                 // From float32.
                 let (low_bound, low_cond, high_bound) = match (signed, out_bits) {
+                    (true, 8) => (
+                        i8::min_value() as f32 - 1.,
+                        FloatCC::GreaterThan,
+                        i8::max_value() as f32 + 1.,
+                    ),
+                    (true, 16) => (
+                        i16::min_value() as f32 - 1.,
+                        FloatCC::GreaterThan,
+                        i16::max_value() as f32 + 1.,
+                    ),
                     (true, 32) => (
                         i32::min_value() as f32, // I32_MIN - 1 isn't precisely representable as a f32.
                         FloatCC::GreaterThanOrEqual,
@@ -2209,6 +2219,8 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                         FloatCC::GreaterThanOrEqual,
                         i64::max_value() as f32 + 1.,
                     ),
+                    (false, 8) => (-1., FloatCC::GreaterThan, u8::max_value() as f32 + 1.),
+                    (false, 16) => (-1., FloatCC::GreaterThan, u16::max_value() as f32 + 1.),
                     (false, 32) => (-1., FloatCC::GreaterThan, u32::max_value() as f32 + 1.),
                     (false, 64) => (-1., FloatCC::GreaterThan, u64::max_value() as f32 + 1.),
                     _ => panic!("Unknown input/output-bits combination"),
@@ -2240,6 +2252,16 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
             } else {
                 // From float64.
                 let (low_bound, low_cond, high_bound) = match (signed, out_bits) {
+                    (true, 8) => (
+                        i8::min_value() as f64 - 1.,
+                        FloatCC::GreaterThan,
+                        i8::max_value() as f64 + 1.,
+                    ),
+                    (true, 16) => (
+                        i16::min_value() as f64 - 1.,
+                        FloatCC::GreaterThan,
+                        i16::max_value() as f64 + 1.,
+                    ),
                     (true, 32) => (
                         i32::min_value() as f64 - 1.,
                         FloatCC::GreaterThan,
@@ -2250,6 +2272,8 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                         FloatCC::GreaterThanOrEqual,
                         i64::max_value() as f64 + 1.,
                     ),
+                    (false, 8) => (-1., FloatCC::GreaterThan, u8::max_value() as f64 + 1.),
+                    (false, 16) => (-1., FloatCC::GreaterThan, u16::max_value() as f64 + 1.),
                     (false, 32) => (-1., FloatCC::GreaterThan, u32::max_value() as f64 + 1.),
                     (false, 64) => (-1., FloatCC::GreaterThan, u64::max_value() as f64 + 1.),
                     _ => panic!("Unknown input/output-bits combination"),
@@ -2289,10 +2313,10 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
             let out_bits = ty_bits(ctx.output_ty(insn, 0));
             let signed = op == Opcode::FcvtFromSint;
             let op = match (signed, in_bits, out_bits) {
-                (false, 32, 32) => IntToFpuOp::U32ToF32,
-                (true, 32, 32) => IntToFpuOp::I32ToF32,
-                (false, 32, 64) => IntToFpuOp::U32ToF64,
-                (true, 32, 64) => IntToFpuOp::I32ToF64,
+                (false, 8, 32) | (false, 16, 32) | (false, 32, 32) => IntToFpuOp::U32ToF32,
+                (true, 8, 32) | (true, 16, 32) | (true, 32, 32) => IntToFpuOp::I32ToF32,
+                (false, 8, 64) | (false, 16, 64) | (false, 32, 64) => IntToFpuOp::U32ToF64,
+                (true, 8, 64) | (true, 16, 64) | (true, 32, 64) => IntToFpuOp::I32ToF64,
                 (false, 64, 32) => IntToFpuOp::U64ToF32,
                 (true, 64, 32) => IntToFpuOp::I64ToF32,
                 (false, 64, 64) => IntToFpuOp::U64ToF64,
@@ -2300,8 +2324,8 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                 _ => panic!("Unknown input/output-bits combination"),
             };
             let narrow_mode = match (signed, in_bits) {
-                (false, 32) => NarrowValueMode::ZeroExtend32,
-                (true, 32) => NarrowValueMode::SignExtend32,
+                (false, 8) | (false, 16) | (false, 32) => NarrowValueMode::ZeroExtend32,
+                (true, 8) | (true, 16) | (true, 32) => NarrowValueMode::SignExtend32,
                 (false, 64) => NarrowValueMode::ZeroExtend64,
                 (true, 64) => NarrowValueMode::SignExtend64,
                 _ => panic!("Unknown input size"),