diff --git a/build.zig b/build.zig
index 731b825c07..a5f4cd5675 100644
--- a/build.zig
+++ b/build.zig
@@ -577,6 +577,10 @@ pub fn build(b: *std.Build) !void {
     } else {
         update_mingw_step.dependOn(&b.addFail("The -Dmingw-src=... option is required for this step").step);
     }
+
+    const test_incremental_step = b.step("test-incremental", "Run the incremental compilation test cases");
+    try tests.addIncrementalTests(b, test_incremental_step);
+    test_step.dependOn(test_incremental_step);
 }
 
 fn addWasiUpdateStep(b: *std.Build, version: [:0]const u8) !void {
diff --git a/lib/std/io.zig b/lib/std/io.zig
index 6455693d67..0a9b2bf867 100644
--- a/lib/std/io.zig
+++ b/lib/std/io.zig
@@ -442,6 +442,7 @@ pub fn poll(
         .overlapped = [1]windows.OVERLAPPED{
             mem.zeroes(windows.OVERLAPPED),
         } ** enum_fields.len,
+        .small_bufs = undefined,
         .active = .{
             .count = 0,
             .handles_buf = undefined,
@@ -481,6 +482,7 @@ pub fn Poller(comptime StreamEnum: type) type {
         windows: if (is_windows) struct {
             first_read_done: bool,
             overlapped: [enum_fields.len]windows.OVERLAPPED,
+            small_bufs: [enum_fields.len][128]u8,
             active: struct {
                 count: math.IntFittingRange(0, enum_fields.len),
                 handles_buf: [enum_fields.len]windows.HANDLE,
@@ -534,24 +536,31 @@ pub fn Poller(comptime StreamEnum: type) type {
             const bump_amt = 512;
 
             if (!self.windows.first_read_done) {
-                // Windows Async IO requires an initial call to ReadFile before waiting on the handle
+                var already_read_data = false;
                 for (0..enum_fields.len) |i| {
                     const handle = self.windows.active.handles_buf[i];
-                    switch (try windowsAsyncRead(
+                    switch (try windowsAsyncReadToFifoAndQueueSmallRead(
                         handle,
                         &self.windows.overlapped[i],
                         &self.fifos[i],
+                        &self.windows.small_bufs[i],
                         bump_amt,
                     )) {
-                        .pending => {
+                        .populated, .empty => |state| {
+                            if (state == .populated) already_read_data = true;
                             self.windows.active.handles_buf[self.windows.active.count] = handle;
                             self.windows.active.stream_map[self.windows.active.count] = @as(StreamEnum, @enumFromInt(i));
                             self.windows.active.count += 1;
                         },
                         .closed => {}, // don't add to the wait_objects list
+                        .closed_populated => {
+                            // don't add to the wait_objects list, but we did already get data
+                            already_read_data = true;
+                        },
                     }
                 }
                 self.windows.first_read_done = true;
+                if (already_read_data) return true;
             }
 
             while (true) {
@@ -576,32 +585,35 @@ pub fn Poller(comptime StreamEnum: type) type {
 
                 const active_idx = status - windows.WAIT_OBJECT_0;
 
-                const handle = self.windows.active.handles_buf[active_idx];
                 const stream_idx = @intFromEnum(self.windows.active.stream_map[active_idx]);
-                var read_bytes: u32 = undefined;
-                if (0 == windows.kernel32.GetOverlappedResult(
-                    handle,
-                    &self.windows.overlapped[stream_idx],
-                    &read_bytes,
-                    0,
-                )) switch (windows.GetLastError()) {
-                    .BROKEN_PIPE => {
+                const handle = self.windows.active.handles_buf[active_idx];
+
+                const overlapped = &self.windows.overlapped[stream_idx];
+                const stream_fifo = &self.fifos[stream_idx];
+                const small_buf = &self.windows.small_bufs[stream_idx];
+
+                const num_bytes_read = switch (try windowsGetReadResult(handle, overlapped, false)) {
+                    .success => |n| n,
+                    .closed => {
                         self.windows.active.removeAt(active_idx);
                         continue;
                     },
-                    else => |err| return windows.unexpectedError(err),
+                    .aborted => unreachable,
                 };
+                try stream_fifo.write(small_buf[0..num_bytes_read]);
 
-                self.fifos[stream_idx].update(read_bytes);
-
-                switch (try windowsAsyncRead(
+                switch (try windowsAsyncReadToFifoAndQueueSmallRead(
                     handle,
-                    &self.windows.overlapped[stream_idx],
-                    &self.fifos[stream_idx],
+                    overlapped,
+                    stream_fifo,
+                    small_buf,
                     bump_amt,
                 )) {
-                    .pending => {},
-                    .closed => self.windows.active.removeAt(active_idx),
+                    .empty => {}, // irrelevant, we already got data from the small buffer
+                    .populated => {},
+                    .closed,
+                    .closed_populated, // identical, since we already got data from the small buffer
+                    => self.windows.active.removeAt(active_idx),
                 }
                 return true;
             }
@@ -654,25 +666,145 @@ pub fn Poller(comptime StreamEnum: type) type {
     };
 }
 
-fn windowsAsyncRead(
+/// The `ReadFile` docuementation states that `lpNumberOfBytesRead` does not have a meaningful
+/// result when using overlapped I/O, but also that it cannot be `null` on Windows 7. For
+/// compatibility, we point it to this dummy variables, which we never otherwise access.
+/// See: https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-readfile
+var win_dummy_bytes_read: u32 = undefined;
+
+/// Read as much data as possible from `handle` with `overlapped`, and write it to the FIFO. Before
+/// returning, queue a read into `small_buf` so that `WaitForMultipleObjects` returns when more data
+/// is available. `handle` must have no pending asynchronous operation.
+fn windowsAsyncReadToFifoAndQueueSmallRead(
     handle: windows.HANDLE,
     overlapped: *windows.OVERLAPPED,
     fifo: *PollFifo,
+    small_buf: *[128]u8,
     bump_amt: usize,
-) !enum { pending, closed } {
+) !enum { empty, populated, closed_populated, closed } {
+    var read_any_data = false;
     while (true) {
-        const buf = try fifo.writableWithSize(bump_amt);
-        var read_bytes: u32 = undefined;
-        const read_result = windows.kernel32.ReadFile(handle, buf.ptr, math.cast(u32, buf.len) orelse math.maxInt(u32), &read_bytes, overlapped);
-        if (read_result == 0) return switch (windows.GetLastError()) {
-            .IO_PENDING => .pending,
-            .BROKEN_PIPE => .closed,
-            else => |err| windows.unexpectedError(err),
+        const fifo_read_pending = while (true) {
+            const buf = try fifo.writableWithSize(bump_amt);
+            const buf_len = math.cast(u32, buf.len) orelse math.maxInt(u32);
+
+            if (0 == windows.kernel32.ReadFile(
+                handle,
+                buf.ptr,
+                buf_len,
+                &win_dummy_bytes_read,
+                overlapped,
+            )) switch (windows.GetLastError()) {
+                .IO_PENDING => break true,
+                .BROKEN_PIPE => return if (read_any_data) .closed_populated else .closed,
+                else => |err| return windows.unexpectedError(err),
+            };
+
+            const num_bytes_read = switch (try windowsGetReadResult(handle, overlapped, false)) {
+                .success => |n| n,
+                .closed => return if (read_any_data) .closed_populated else .closed,
+                .aborted => unreachable,
+            };
+
+            read_any_data = true;
+            fifo.update(num_bytes_read);
+
+            if (num_bytes_read == buf_len) {
+                // We filled the buffer, so there's probably more data available.
+                continue;
+            } else {
+                // We didn't fill the buffer, so assume we're out of data.
+                // There is no pending read.
+                break false;
+            }
         };
-        fifo.update(read_bytes);
+
+        if (fifo_read_pending) cancel_read: {
+            // Cancel the pending read into the FIFO.
+            _ = windows.kernel32.CancelIo(handle);
+
+            // We have to wait for the handle to be signalled, i.e. for the cancellation to complete.
+            switch (windows.kernel32.WaitForSingleObject(handle, windows.INFINITE)) {
+                windows.WAIT_OBJECT_0 => {},
+                windows.WAIT_FAILED => return windows.unexpectedError(windows.GetLastError()),
+                else => unreachable,
+            }
+
+            // If it completed before we canceled, make sure to tell the FIFO!
+            const num_bytes_read = switch (try windowsGetReadResult(handle, overlapped, true)) {
+                .success => |n| n,
+                .closed => return if (read_any_data) .closed_populated else .closed,
+                .aborted => break :cancel_read,
+            };
+            read_any_data = true;
+            fifo.update(num_bytes_read);
+        }
+
+        // Try to queue the 1-byte read.
+        if (0 == windows.kernel32.ReadFile(
+            handle,
+            small_buf,
+            small_buf.len,
+            &win_dummy_bytes_read,
+            overlapped,
+        )) switch (windows.GetLastError()) {
+            .IO_PENDING => {
+                // 1-byte read pending as intended
+                return if (read_any_data) .populated else .empty;
+            },
+            .BROKEN_PIPE => return if (read_any_data) .closed_populated else .closed,
+            else => |err| return windows.unexpectedError(err),
+        };
+
+        // We got data back this time. Write it to the FIFO and run the main loop again.
+        const num_bytes_read = switch (try windowsGetReadResult(handle, overlapped, false)) {
+            .success => |n| n,
+            .closed => return if (read_any_data) .closed_populated else .closed,
+            .aborted => unreachable,
+        };
+        try fifo.write(small_buf[0..num_bytes_read]);
+        read_any_data = true;
     }
 }
 
+/// Simple wrapper around `GetOverlappedResult` to determine the result of a `ReadFile` operation.
+/// If `!allow_aborted`, then `aborted` is never returned (`OPERATION_ABORTED` is considered unexpected).
+///
+/// The `ReadFile` documentation states that the number of bytes read by an overlapped `ReadFile` must be determined using `GetOverlappedResult`, even if the
+/// operation immediately returns data:
+/// "Use NULL for [lpNumberOfBytesRead] if this is an asynchronous operation to avoid potentially
+/// erroneous results."
+/// "If `hFile` was opened with `FILE_FLAG_OVERLAPPED`, the following conditions are in effect: [...]
+/// The lpNumberOfBytesRead parameter should be set to NULL. Use the GetOverlappedResult function to
+/// get the actual number of bytes read."
+/// See: https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-readfile
+fn windowsGetReadResult(
+    handle: windows.HANDLE,
+    overlapped: *windows.OVERLAPPED,
+    allow_aborted: bool,
+) !union(enum) {
+    success: u32,
+    closed,
+    aborted,
+} {
+    var num_bytes_read: u32 = undefined;
+    if (0 == windows.kernel32.GetOverlappedResult(
+        handle,
+        overlapped,
+        &num_bytes_read,
+        0,
+    )) switch (windows.GetLastError()) {
+        .BROKEN_PIPE => return .closed,
+        .OPERATION_ABORTED => |err| if (allow_aborted) {
+            return .aborted;
+        } else {
+            return windows.unexpectedError(err);
+        },
+        else => |err| return windows.unexpectedError(err),
+    };
+    return .{ .success = num_bytes_read };
+}
+
 /// Given an enum, returns a struct with fields of that enum, each field
 /// representing an I/O stream for polling.
 pub fn PollFiles(comptime StreamEnum: type) type {
diff --git a/test/incremental/add_decl b/test/incremental/add_decl
index 1f9788f481..6b3a0dad84 100644
--- a/test/incremental/add_decl
+++ b/test/incremental/add_decl
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 const std = @import("std");
diff --git a/test/incremental/add_decl_namespaced b/test/incremental/add_decl_namespaced
index 7063e3fa74..48ed5cfd2e 100644
--- a/test/incremental/add_decl_namespaced
+++ b/test/incremental/add_decl_namespaced
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 const std = @import("std");
diff --git a/test/incremental/delete_comptime_decls b/test/incremental/delete_comptime_decls
index 54411797cf..03ddc68128 100644
--- a/test/incremental/delete_comptime_decls
+++ b/test/incremental/delete_comptime_decls
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 pub fn main() void {}
diff --git a/test/incremental/hello b/test/incremental/hello
index 9419b3d186..3526b47f7c 100644
--- a/test/incremental/hello
+++ b/test/incremental/hello
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 const std = @import("std");
diff --git a/test/incremental/modify_inline_fn b/test/incremental/modify_inline_fn
index 69ab1f429a..cd5361fb17 100644
--- a/test/incremental/modify_inline_fn
+++ b/test/incremental/modify_inline_fn
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 const std = @import("std");
diff --git a/test/incremental/move_src b/test/incremental/move_src
index 8a3a24a269..908135485c 100644
--- a/test/incremental/move_src
+++ b/test/incremental/move_src
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 const std = @import("std");
diff --git a/test/incremental/remove_enum_field b/test/incremental/remove_enum_field
index c163e5e168..3a882ae0f1 100644
--- a/test/incremental/remove_enum_field
+++ b/test/incremental/remove_enum_field
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 const MyEnum = enum(u8) {
diff --git a/test/incremental/type_becomes_comptime_only b/test/incremental/type_becomes_comptime_only
index 3878e0c61b..2da31ec5f2 100644
--- a/test/incremental/type_becomes_comptime_only
+++ b/test/incremental/type_becomes_comptime_only
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 const SomeType = u32;
diff --git a/test/incremental/unreferenced_error b/test/incremental/unreferenced_error
index 2031975986..3dfe0ab758 100644
--- a/test/incremental/unreferenced_error
+++ b/test/incremental/unreferenced_error
@@ -1,5 +1,6 @@
 #target=x86_64-linux-selfhosted
 #target=x86_64-linux-cbe
+#target=x86_64-windows-cbe
 #update=initial version
 #file=main.zig
 const std = @import("std");
diff --git a/test/tests.zig b/test/tests.zig
index 1e98a48489..017f9478a9 100644
--- a/test/tests.zig
+++ b/test/tests.zig
@@ -1509,3 +1509,31 @@ pub fn addDebuggerTests(b: *std.Build, options: DebuggerContext.Options) ?*Step
     });
     return step;
 }
+
+pub fn addIncrementalTests(b: *std.Build, test_step: *Step) !void {
+    const incr_check = b.addExecutable(.{
+        .name = "incr-check",
+        .root_source_file = b.path("tools/incr-check.zig"),
+        .target = b.graph.host,
+        .optimize = .Debug,
+    });
+
+    var dir = try b.build_root.handle.openDir("test/incremental", .{ .iterate = true });
+    defer dir.close();
+
+    var it = try dir.walk(b.graph.arena);
+    while (try it.next()) |entry| {
+        if (entry.kind != .file) continue;
+
+        const run = b.addRunArtifact(incr_check);
+        run.setName(b.fmt("incr-check '{s}'", .{entry.basename}));
+
+        run.addArg(b.graph.zig_exe);
+        run.addFileArg(b.path("test/incremental/").path(b, entry.path));
+        run.addArgs(&.{ "--zig-lib-dir", b.fmt("{}", .{b.graph.zig_lib_directory}) });
+
+        run.addCheck(.{ .expect_term = .{ .Exited = 0 } });
+
+        test_step.dependOn(&run.step);
+    }
+}
diff --git a/tools/incr-check.zig b/tools/incr-check.zig
index 047b129276..b5329f134e 100644
--- a/tools/incr-check.zig
+++ b/tools/incr-check.zig
@@ -1,11 +1,12 @@
 const std = @import("std");
-const fatal = std.process.fatal;
 const Allocator = std.mem.Allocator;
 const Cache = std.Build.Cache;
 
-const usage = "usage: incr-check <zig binary path> <input file> [--zig-lib-dir lib] [--debug-zcu] [--debug-link] [--zig-cc-binary /path/to/zig]";
+const usage = "usage: incr-check <zig binary path> <input file> [--zig-lib-dir lib] [--debug-zcu] [--debug-link] [--preserve-tmp] [--zig-cc-binary /path/to/zig]";
 
 pub fn main() !void {
+    const fatal = std.process.fatal;
+
     var arena_instance = std.heap.ArenaAllocator.init(std.heap.page_allocator);
     defer arena_instance.deinit();
     const arena = arena_instance.allocator();
@@ -16,6 +17,7 @@ pub fn main() !void {
     var opt_cc_zig: ?[]const u8 = null;
     var debug_zcu = false;
     var debug_link = false;
+    var preserve_tmp = false;
 
     var arg_it = try std.process.argsWithAllocator(arena);
     _ = arg_it.skip();
@@ -27,6 +29,8 @@ pub fn main() !void {
                 debug_zcu = true;
             } else if (std.mem.eql(u8, arg, "--debug-link")) {
                 debug_link = true;
+            } else if (std.mem.eql(u8, arg, "--preserve-tmp")) {
+                preserve_tmp = true;
             } else if (std.mem.eql(u8, arg, "--zig-cc-binary")) {
                 opt_cc_zig = arg_it.next() orelse fatal("expect arg after '--zig-cc-binary'\n{s}", .{usage});
             } else {
@@ -48,15 +52,29 @@ pub fn main() !void {
     const input_file_bytes = try std.fs.cwd().readFileAlloc(arena, input_file_name, std.math.maxInt(u32));
     const case = try Case.parse(arena, input_file_bytes);
 
+    // Check now: if there are any targets using the `cbe` backend, we need the lib dir.
+    if (opt_lib_dir == null) {
+        for (case.targets) |target| {
+            if (target.backend == .cbe) {
+                fatal("'--zig-lib-dir' requried when using backend 'cbe'", .{});
+            }
+        }
+    }
+
     const prog_node = std.Progress.start(.{});
     defer prog_node.end();
 
     const rand_int = std.crypto.random.int(u64);
     const tmp_dir_path = "tmp_" ++ std.fmt.hex(rand_int);
-    const tmp_dir = try std.fs.cwd().makeOpenPath(tmp_dir_path, .{});
-
-    const child_prog_node = prog_node.start("zig build-exe", 0);
-    defer child_prog_node.end();
+    var tmp_dir = try std.fs.cwd().makeOpenPath(tmp_dir_path, .{});
+    defer {
+        tmp_dir.close();
+        if (!preserve_tmp) {
+            std.fs.cwd().deleteTree(tmp_dir_path) catch |err| {
+                std.log.warn("failed to delete tree '{s}': {s}", .{ tmp_dir_path, @errorName(err) });
+            };
+        }
+    }
 
     // Convert paths to be relative to the cwd of the subprocess.
     const resolved_zig_exe = try std.fs.path.relative(arena, tmp_dir_path, zig_exe);
@@ -65,10 +83,21 @@ pub fn main() !void {
     else
         null;
 
+    const host = try std.zig.system.resolveTargetQuery(.{});
+
     const debug_log_verbose = debug_zcu or debug_link;
 
     for (case.targets) |target| {
-        std.log.scoped(.status).info("target: '{s}-{s}'", .{ target.query, @tagName(target.backend) });
+        const target_prog_node = node: {
+            var name_buf: [std.Progress.Node.max_name_len]u8 = undefined;
+            const name = std.fmt.bufPrint(&name_buf, "{s}-{s}", .{ target.query, @tagName(target.backend) }) catch &name_buf;
+            break :node prog_node.start(name, case.updates.len);
+        };
+        defer target_prog_node.end();
+
+        if (debug_log_verbose) {
+            std.log.scoped(.status).info("target: '{s}-{s}'", .{ target.query, @tagName(target.backend) });
+        }
 
         var child_args: std.ArrayListUnmanaged([]const u8) = .empty;
         try child_args.appendSlice(arena, &.{
@@ -81,7 +110,7 @@ pub fn main() !void {
             "--cache-dir",
             ".local-cache",
             "--global-cache-dir",
-            ".global_cache",
+            ".global-cache",
             "--listen=-",
         });
         if (opt_resolved_lib_dir) |resolved_lib_dir| {
@@ -100,11 +129,14 @@ pub fn main() !void {
             try child_args.appendSlice(arena, &.{ "--debug-log", "link", "--debug-log", "link_state", "--debug-log", "link_relocs" });
         }
 
+        const zig_prog_node = target_prog_node.start("zig build-exe", 0);
+        defer zig_prog_node.end();
+
         var child = std.process.Child.init(child_args.items, arena);
         child.stdin_behavior = .Pipe;
         child.stdout_behavior = .Pipe;
         child.stderr_behavior = .Pipe;
-        child.progress_node = child_prog_node;
+        child.progress_node = zig_prog_node;
         child.cwd_dir = tmp_dir;
         child.cwd = tmp_dir_path;
 
@@ -121,7 +153,7 @@ pub fn main() !void {
                 "-target",
                 target.query,
                 "-I",
-                opt_resolved_lib_dir orelse fatal("'--zig-lib-dir' required when using backend 'cbe'", .{}),
+                opt_resolved_lib_dir.?, // verified earlier
                 "-o",
             });
         }
@@ -129,11 +161,13 @@ pub fn main() !void {
         var eval: Eval = .{
             .arena = arena,
             .case = case,
+            .host = host,
             .target = target,
             .tmp_dir = tmp_dir,
             .tmp_dir_path = tmp_dir_path,
             .child = &child,
             .allow_stderr = debug_log_verbose,
+            .preserve_tmp_on_fatal = preserve_tmp,
             .cc_child_args = &cc_child_args,
         };
 
@@ -146,7 +180,7 @@ pub fn main() !void {
         defer poller.deinit();
 
         for (case.updates) |update| {
-            var update_node = prog_node.start(update.name, 0);
+            var update_node = target_prog_node.start(update.name, 0);
             defer update_node.end();
 
             if (debug_log_verbose) {
@@ -160,18 +194,20 @@ pub fn main() !void {
 
         try eval.end(&poller);
 
-        waitChild(&child);
+        waitChild(&child, &eval);
     }
 }
 
 const Eval = struct {
     arena: Allocator,
+    host: std.Target,
     case: Case,
     target: Case.Target,
     tmp_dir: std.fs.Dir,
     tmp_dir_path: []const u8,
     child: *std.process.Child,
     allow_stderr: bool,
+    preserve_tmp_on_fatal: bool,
     /// When `target.backend == .cbe`, this contains the first few arguments to `zig cc` to build the generated binary.
     /// The arguments `out.c in.c` must be appended before spawning the subprocess.
     cc_child_args: *std.ArrayListUnmanaged([]const u8),
@@ -186,12 +222,12 @@ const Eval = struct {
                 .sub_path = full_contents.name,
                 .data = full_contents.bytes,
             }) catch |err| {
-                fatal("failed to update '{s}': {s}", .{ full_contents.name, @errorName(err) });
+                eval.fatal("failed to update '{s}': {s}", .{ full_contents.name, @errorName(err) });
             };
         }
         for (update.deletes) |doomed_name| {
             eval.tmp_dir.deleteFile(doomed_name) catch |err| {
-                fatal("failed to delete '{s}': {s}", .{ doomed_name, @errorName(err) });
+                eval.fatal("failed to delete '{s}': {s}", .{ doomed_name, @errorName(err) });
             };
         }
     }
@@ -233,7 +269,7 @@ const Eval = struct {
                         if (eval.allow_stderr) {
                             std.log.info("error_bundle included stderr:\n{s}", .{stderr_data});
                         } else {
-                            fatal("error_bundle included unexpected stderr:\n{s}", .{stderr_data});
+                            eval.fatal("error_bundle included unexpected stderr:\n{s}", .{stderr_data});
                         }
                     }
                     if (result_error_bundle.errorMessageCount() != 0) {
@@ -252,7 +288,7 @@ const Eval = struct {
                         if (eval.allow_stderr) {
                             std.log.info("emit_digest included stderr:\n{s}", .{stderr_data});
                         } else {
-                            fatal("emit_digest included unexpected stderr:\n{s}", .{stderr_data});
+                            eval.fatal("emit_digest included unexpected stderr:\n{s}", .{stderr_data});
                         }
                     }
 
@@ -268,14 +304,7 @@ const Eval = struct {
                     const name = std.fs.path.stem(std.fs.path.basename(eval.case.root_source_file));
                     const bin_name = try std.zig.binNameAlloc(arena, .{
                         .root_name = name,
-                        .target = try std.zig.system.resolveTargetQuery(try std.Build.parseTargetQuery(.{
-                            .arch_os_abi = eval.target.query,
-                            .object_format = switch (eval.target.backend) {
-                                .sema => unreachable,
-                                .selfhosted, .llvm => null,
-                                .cbe => "c",
-                            },
-                        })),
+                        .target = eval.target.resolved,
                         .output_mode = .Exe,
                     });
                     const bin_path = try std.fs.path.join(arena, &.{ result_dir, bin_name });
@@ -296,16 +325,15 @@ const Eval = struct {
             if (eval.allow_stderr) {
                 std.log.info("update '{s}' included stderr:\n{s}", .{ update.name, stderr_data });
             } else {
-                fatal("update '{s}' failed:\n{s}", .{ update.name, stderr_data });
+                eval.fatal("update '{s}' failed:\n{s}", .{ update.name, stderr_data });
             }
         }
 
-        waitChild(eval.child);
-        fatal("update '{s}': compiler failed to send error_bundle or emit_bin_path", .{update.name});
+        waitChild(eval.child, eval);
+        eval.fatal("update '{s}': compiler failed to send error_bundle or emit_bin_path", .{update.name});
     }
 
     fn checkErrorOutcome(eval: *Eval, update: Case.Update, error_bundle: std.zig.ErrorBundle) !void {
-        _ = eval;
         switch (update.outcome) {
             .unknown => return,
             .compile_errors => |expected_errors| {
@@ -317,7 +345,7 @@ const Eval = struct {
             .stdout, .exit_code => {
                 const color: std.zig.Color = .auto;
                 error_bundle.renderToStdErr(color.renderOptions());
-                fatal("update '{s}': unexpected compile errors", .{update.name});
+                eval.fatal("update '{s}': unexpected compile errors", .{update.name});
             },
         }
     }
@@ -325,7 +353,7 @@ const Eval = struct {
     fn checkSuccessOutcome(eval: *Eval, update: Case.Update, opt_emitted_path: ?[]const u8, prog_node: std.Progress.Node) !void {
         switch (update.outcome) {
             .unknown => return,
-            .compile_errors => fatal("expected compile errors but compilation incorrectly succeeded", .{}),
+            .compile_errors => eval.fatal("expected compile errors but compilation incorrectly succeeded", .{}),
             .stdout, .exit_code => {},
         }
         const emitted_path = opt_emitted_path orelse {
@@ -344,27 +372,73 @@ const Eval = struct {
             },
         };
 
+        var argv_buf: [2][]const u8 = undefined;
+        const argv: []const []const u8, const is_foreign: bool = switch (std.zig.system.getExternalExecutor(
+            eval.host,
+            &eval.target.resolved,
+            .{ .link_libc = eval.target.backend == .cbe },
+        )) {
+            .bad_dl, .bad_os_or_cpu => {
+                // This binary cannot be executed on this host.
+                if (eval.allow_stderr) {
+                    std.log.warn("skipping execution because host '{s}' cannot execute binaries for foreign target '{s}'", .{
+                        try eval.host.zigTriple(eval.arena),
+                        try eval.target.resolved.zigTriple(eval.arena),
+                    });
+                }
+                return;
+            },
+            .native, .rosetta => argv: {
+                argv_buf[0] = binary_path;
+                break :argv .{ argv_buf[0..1], false };
+            },
+            .qemu, .wine, .wasmtime, .darling => |executor_cmd| argv: {
+                argv_buf[0] = executor_cmd;
+                argv_buf[1] = binary_path;
+                break :argv .{ argv_buf[0..2], true };
+            },
+        };
+
+        const run_prog_node = prog_node.start("run generated executable", 0);
+        defer run_prog_node.end();
+
         const result = std.process.Child.run(.{
             .allocator = eval.arena,
-            .argv = &.{binary_path},
+            .argv = argv,
             .cwd_dir = eval.tmp_dir,
             .cwd = eval.tmp_dir_path,
         }) catch |err| {
-            fatal("update '{s}': failed to run the generated executable '{s}': {s}", .{
+            if (is_foreign) {
+                // Chances are the foreign executor isn't available. Skip this evaluation.
+                if (eval.allow_stderr) {
+                    std.log.warn("update '{s}': skipping execution of '{s}' via executor for foreign target '{s}': {s}", .{
+                        update.name,
+                        binary_path,
+                        try eval.target.resolved.zigTriple(eval.arena),
+                        @errorName(err),
+                    });
+                }
+                return;
+            }
+            eval.fatal("update '{s}': failed to run the generated executable '{s}': {s}", .{
                 update.name, binary_path, @errorName(err),
             });
         };
-        if (result.stderr.len != 0) {
+
+        // Some executors (looking at you, Wine) like throwing some stderr in, just for fun.
+        // Therefore, we'll ignore stderr when using a foreign executor.
+        if (!is_foreign and result.stderr.len != 0) {
             std.log.err("update '{s}': generated executable '{s}' had unexpected stderr:\n{s}", .{
                 update.name, binary_path, result.stderr,
             });
         }
+
         switch (result.term) {
             .Exited => |code| switch (update.outcome) {
                 .unknown, .compile_errors => unreachable,
                 .stdout => |expected_stdout| {
                     if (code != 0) {
-                        fatal("update '{s}': generated executable '{s}' failed with code {d}", .{
+                        eval.fatal("update '{s}': generated executable '{s}' failed with code {d}", .{
                             update.name, binary_path, code,
                         });
                     }
@@ -373,12 +447,13 @@ const Eval = struct {
                 .exit_code => |expected_code| try std.testing.expectEqual(expected_code, result.term.Exited),
             },
             .Signal, .Stopped, .Unknown => {
-                fatal("update '{s}': generated executable '{s}' terminated unexpectedly", .{
+                eval.fatal("update '{s}': generated executable '{s}' terminated unexpectedly", .{
                     update.name, binary_path,
                 });
             },
         }
-        if (result.stderr.len != 0) std.process.exit(1);
+
+        if (!is_foreign and result.stderr.len != 0) std.process.exit(1);
     }
 
     fn requestUpdate(eval: *Eval) !void {
@@ -390,7 +465,7 @@ const Eval = struct {
     }
 
     fn end(eval: *Eval, poller: *Poller) !void {
-        requestExit(eval.child);
+        requestExit(eval.child, eval);
 
         const Header = std.zig.Server.Message.Header;
         const stdout = poller.fifo(.stdout);
@@ -410,7 +485,7 @@ const Eval = struct {
 
         if (stderr.readableLength() > 0) {
             const stderr_data = try stderr.toOwnedSlice();
-            fatal("unexpected stderr:\n{s}", .{stderr_data});
+            eval.fatal("unexpected stderr:\n{s}", .{stderr_data});
         }
     }
 
@@ -430,7 +505,7 @@ const Eval = struct {
             .cwd = eval.tmp_dir_path,
             .progress_node = child_prog_node,
         }) catch |err| {
-            fatal("update '{s}': failed to spawn zig cc for '{s}': {s}", .{
+            eval.fatal("update '{s}': failed to spawn zig cc for '{s}': {s}", .{
                 update.name, c_path, @errorName(err),
             });
         };
@@ -441,7 +516,7 @@ const Eval = struct {
                         update.name, result.stderr,
                     });
                 }
-                fatal("update '{s}': zig cc for '{s}' failed with code {d}", .{
+                eval.fatal("update '{s}': zig cc for '{s}' failed with code {d}", .{
                     update.name, c_path, code,
                 });
             },
@@ -451,12 +526,22 @@ const Eval = struct {
                         update.name, result.stderr,
                     });
                 }
-                fatal("update '{s}': zig cc for '{s}' terminated unexpectedly", .{
+                eval.fatal("update '{s}': zig cc for '{s}' terminated unexpectedly", .{
                     update.name, c_path,
                 });
             },
         }
     }
+
+    fn fatal(eval: *Eval, comptime fmt: []const u8, args: anytype) noreturn {
+        eval.tmp_dir.close();
+        if (!eval.preserve_tmp_on_fatal) {
+            std.fs.cwd().deleteTree(eval.tmp_dir_path) catch |err| {
+                std.log.warn("failed to delete tree '{s}': {s}", .{ eval.tmp_dir_path, @errorName(err) });
+            };
+        }
+        std.process.fatal(fmt, args);
+    }
 };
 
 const Case = struct {
@@ -466,6 +551,7 @@ const Case = struct {
 
     const Target = struct {
         query: []const u8,
+        resolved: std.Target,
         backend: Backend,
         const Backend = enum {
             /// Run semantic analysis only. Runtime output will not be tested, but we still verify
@@ -511,6 +597,8 @@ const Case = struct {
     };
 
     fn parse(arena: Allocator, bytes: []const u8) !Case {
+        const fatal = std.process.fatal;
+
         var targets: std.ArrayListUnmanaged(Target) = .empty;
         var updates: std.ArrayListUnmanaged(Update) = .empty;
         var changes: std.ArrayListUnmanaged(FullContents) = .empty;
@@ -521,18 +609,32 @@ const Case = struct {
             if (std.mem.startsWith(u8, line, "#")) {
                 var line_it = std.mem.splitScalar(u8, line, '=');
                 const key = line_it.first()[1..];
-                const val = line_it.rest();
+                const val = std.mem.trimRight(u8, line_it.rest(), "\r"); // windows moment
                 if (val.len == 0) {
                     fatal("line {d}: missing value", .{line_n});
                 } else if (std.mem.eql(u8, key, "target")) {
                     const split_idx = std.mem.lastIndexOfScalar(u8, val, '-') orelse
                         fatal("line {d}: target does not include backend", .{line_n});
+
                     const query = val[0..split_idx];
+
                     const backend_str = val[split_idx + 1 ..];
                     const backend: Target.Backend = std.meta.stringToEnum(Target.Backend, backend_str) orelse
                         fatal("line {d}: invalid backend '{s}'", .{ line_n, backend_str });
+
+                    const parsed_query = std.Build.parseTargetQuery(.{
+                        .arch_os_abi = query,
+                        .object_format = switch (backend) {
+                            .sema, .selfhosted, .llvm => null,
+                            .cbe => "c",
+                        },
+                    }) catch fatal("line {d}: invalid target query '{s}'", .{ line_n, query });
+
+                    const resolved = try std.zig.system.resolveTargetQuery(parsed_query);
+
                     try targets.append(arena, .{
                         .query = query,
+                        .resolved = resolved,
                         .backend = backend,
                     });
                 } else if (std.mem.eql(u8, key, "update")) {
@@ -603,7 +705,7 @@ const Case = struct {
     }
 };
 
-fn requestExit(child: *std.process.Child) void {
+fn requestExit(child: *std.process.Child, eval: *Eval) void {
     if (child.stdin == null) return;
 
     const header: std.zig.Client.Message.Header = .{
@@ -612,7 +714,7 @@ fn requestExit(child: *std.process.Child) void {
     };
     child.stdin.?.writeAll(std.mem.asBytes(&header)) catch |err| switch (err) {
         error.BrokenPipe => {},
-        else => fatal("failed to send exit: {s}", .{@errorName(err)}),
+        else => eval.fatal("failed to send exit: {s}", .{@errorName(err)}),
     };
 
     // Send EOF to stdin.
@@ -620,11 +722,11 @@ fn requestExit(child: *std.process.Child) void {
     child.stdin = null;
 }
 
-fn waitChild(child: *std.process.Child) void {
-    requestExit(child);
-    const term = child.wait() catch |err| fatal("child process failed: {s}", .{@errorName(err)});
+fn waitChild(child: *std.process.Child, eval: *Eval) void {
+    requestExit(child, eval);
+    const term = child.wait() catch |err| eval.fatal("child process failed: {s}", .{@errorName(err)});
     switch (term) {
-        .Exited => |code| if (code != 0) fatal("compiler failed with code {d}", .{code}),
-        .Signal, .Stopped, .Unknown => fatal("compiler terminated unexpectedly", .{}),
+        .Exited => |code| if (code != 0) eval.fatal("compiler failed with code {d}", .{code}),
+        .Signal, .Stopped, .Unknown => eval.fatal("compiler terminated unexpectedly", .{}),
     }
 }