diff --git a/src/value.zig b/src/value.zig
index 47f69b2099..4c6a64eefc 100644
--- a/src/value.zig
+++ b/src/value.zig
@@ -1300,16 +1300,16 @@ pub const Value = extern union {
         for (fields) |field, i| {
             const field_val = field_vals[i];
             const field_bigint_const = switch (field.ty.zigTypeTag()) {
-                .Float => switch (field.ty.floatBits(target)) {
-                    16 => bitcastFloatToBigInt(f16, field_val.toFloat(f16), &field_buf),
-                    32 => bitcastFloatToBigInt(f32, field_val.toFloat(f32), &field_buf),
-                    64 => bitcastFloatToBigInt(f64, field_val.toFloat(f64), &field_buf),
-                    80 => bitcastFloatToBigInt(f80, field_val.toFloat(f80), &field_buf),
-                    128 => bitcastFloatToBigInt(f128, field_val.toFloat(f128), &field_buf),
-                    else => unreachable,
+                .Void => continue,
+                .Float => floatToBigInt(field_val, field.ty, target, &field_buf),
+                .Int, .Bool => intOrBoolToBigInt(field_val, field.ty, target, &field_buf, &field_space),
+                .Struct => switch (field.ty.containerLayout()) {
+                    .Auto, .Extern => unreachable, // Sema should have error'd before this.
+                    .Packed => packedStructToInt(field_val, field.ty, target, &field_buf),
                 },
-                .Int, .Bool => field_val.toBigInt(&field_space, target),
-                .Struct => packedStructToInt(field_val, field.ty, target, &field_buf),
+                .Vector => vectorToBigInt(field_val, field.ty, target, &field_buf),
+                .Enum => enumToBigInt(field_val, field.ty, target, &field_space),
+                .Union => unreachable, // TODO: packed structs support packed unions
                 else => unreachable,
             };
             var field_bigint = BigIntMutable.init(&field_buf2, 0);
@@ -1320,6 +1320,61 @@ pub const Value = extern union {
         return bigint.toConst();
     }
 
+    fn intOrBoolToBigInt(val: Value, ty: Type, target: Target, buf: []std.math.big.Limb, space: *BigIntSpace) BigIntConst {
+        const big_int_const = val.toBigInt(space, target);
+        if (big_int_const.positive) return big_int_const;
+
+        var big_int = BigIntMutable.init(buf, 0);
+        big_int.bitNotWrap(big_int_const.negate(), .unsigned, @intCast(u32, ty.bitSize(target)));
+        big_int.addScalar(big_int.toConst(), 1);
+        return big_int.toConst();
+    }
+
+    fn vectorToBigInt(val: Value, ty: Type, target: Target, buf: []std.math.big.Limb) BigIntConst {
+        const endian = target.cpu.arch.endian();
+        var vec_bitint = BigIntMutable.init(buf, 0);
+        const vec_len = @intCast(usize, ty.arrayLen());
+        const elem_ty = ty.childType();
+        const elem_size = @intCast(usize, elem_ty.bitSize(target));
+
+        var elem_buf: [16]std.math.big.Limb = undefined;
+        var elem_space: BigIntSpace = undefined;
+        var elem_buf2: [16]std.math.big.Limb = undefined;
+
+        var elem_i: usize = 0;
+        while (elem_i < vec_len) : (elem_i += 1) {
+            const elem_i_target = if (endian == .Big) vec_len - elem_i - 1 else elem_i;
+            const elem_val = val.indexVectorlike(elem_i_target);
+            const elem_bigint_const = switch (elem_ty.zigTypeTag()) {
+                .Int, .Bool => intOrBoolToBigInt(elem_val, elem_ty, target, &elem_buf, &elem_space),
+                .Float => floatToBigInt(elem_val, elem_ty, target, &elem_buf),
+                .Pointer => unreachable, // TODO
+                else => unreachable, // Sema should not let this happen
+            };
+            var elem_bitint = BigIntMutable.init(&elem_buf2, 0);
+            elem_bitint.shiftLeft(elem_bigint_const, elem_size * elem_i);
+            vec_bitint.bitOr(vec_bitint.toConst(), elem_bitint.toConst());
+        }
+        return vec_bitint.toConst();
+    }
+
+    fn enumToBigInt(val: Value, ty: Type, target: Target, space: *BigIntSpace) BigIntConst {
+        var enum_buf: Payload.U64 = undefined;
+        const int_val = val.enumToInt(ty, &enum_buf);
+        return int_val.toBigInt(space, target);
+    }
+
+    fn floatToBigInt(val: Value, ty: Type, target: Target, buf: []std.math.big.Limb) BigIntConst {
+        return switch (ty.floatBits(target)) {
+            16 => bitcastFloatToBigInt(f16, val.toFloat(f16), buf),
+            32 => bitcastFloatToBigInt(f32, val.toFloat(f32), buf),
+            64 => bitcastFloatToBigInt(f64, val.toFloat(f64), buf),
+            80 => bitcastFloatToBigInt(f80, val.toFloat(f80), buf),
+            128 => bitcastFloatToBigInt(f128, val.toFloat(f128), buf),
+            else => unreachable,
+        };
+    }
+
     fn bitcastFloatToBigInt(comptime F: type, f: F, buf: []std.math.big.Limb) BigIntConst {
         const Int = @Type(.{ .Int = .{
             .signedness = .unsigned,
diff --git a/test/behavior/bitcast.zig b/test/behavior/bitcast.zig
index 3a7719191d..c629a1a34b 100644
--- a/test/behavior/bitcast.zig
+++ b/test/behavior/bitcast.zig
@@ -282,3 +282,28 @@ test "@bitCast packed struct of floats" {
     try S.doTheTest();
     comptime try S.doTheTest();
 }
+
+test "comptime @bitCast packed struct to int" {
+    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_c) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
+    if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest;
+
+    const S = packed struct {
+        @"void": void = {},
+        uint: u8 = 13,
+        uint_bit_aligned: u3 = 2,
+        iint_pos: i4 = 1,
+        iint_neg4: i3 = -4,
+        iint_neg2: i3 = -2,
+        float: f32 = 3.14,
+        @"enum": enum(u2) { A, B = 1, C, D } = .B,
+        vectorb: @Vector(3, bool) = .{ true, false, true },
+        vectori: @Vector(2, u8) = .{ 127, 42 },
+        vectorf: @Vector(2, f16) = .{ 3.14, 2.71 },
+    };
+    const Int = @typeInfo(S).Struct.backing_integer.?;
+    var s: S = .{};
+    try expectEqual(@bitCast(Int, s), comptime @bitCast(Int, S{}));
+}