diff --git a/Cargo.lock b/Cargo.lock
index 1ce9784ff3..e3f454df96 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5280,6 +5280,21 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "valgrind"
+version = "0.1.0"
+dependencies = [
+ "bumpalo",
+ "cli_utils",
+ "roc_build",
+ "roc_cli",
+ "roc_load",
+ "roc_mono",
+ "roc_packaging",
+ "roc_reporting",
+ "target-lexicon",
+]
+
 [[package]]
 name = "valuable"
 version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index b007bf7624..4a38ec1f7a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,6 +17,7 @@ members = [
     "crates/repl_wasm",
     "crates/repl_expect",
     "crates/test_utils",
+    "crates/valgrind",
     "crates/tracing",
     "crates/utils",
     "crates/docs",
diff --git a/crates/valgrind/Cargo.toml b/crates/valgrind/Cargo.toml
new file mode 100644
index 0000000000..77230f3406
--- /dev/null
+++ b/crates/valgrind/Cargo.toml
@@ -0,0 +1,20 @@
+[package]
+name = "valgrind"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[dependencies]
+roc_cli = { path = "../cli" } # depend on CLI to prevent cyclic dependencies
+cli_utils = { path = "../cli_utils" }
+roc_build = { path = "../compiler/build" }
+roc_mono = { path = "../compiler/mono" }
+roc_load = { path = "../compiler/load" }
+roc_reporting = { path = "../reporting" }
+roc_packaging = { path = "../packaging" }
+bumpalo.workspace = true
+target-lexicon.workspace = true
+
+[build-dependencies]
+roc_cli = { path = "../cli" } # depend on CLI to prevent cyclic dependencies
+cli_utils = { path = "../cli_utils" }
diff --git a/crates/valgrind/build.rs b/crates/valgrind/build.rs
new file mode 100644
index 0000000000..7d40fc68d3
--- /dev/null
+++ b/crates/valgrind/build.rs
@@ -0,0 +1,22 @@
+fn main() {
+    // goal: build the platform, so tests can use `precompiled-platform=true`
+
+    // first, make sure the roc binary is up to data
+    // cli_utils::helpers::build_roc_bin_cached();
+
+    // next, we just compile one of our examples
+    let roc_path = std::path::Path::new("../../target/debug/roc");
+    let out = cli_utils::helpers::run_roc_with_stdin_and_env(
+        roc_path,
+        &["run", "tests/str_concat_1.roc"],
+        &[],
+        &[],
+    );
+
+    if !out.status.success() {
+        panic!(
+            "Building platform with `{:?}` failed!\n\n{}\n\n{}",
+            out.cmd_str, out.stdout, out.stderr
+        );
+    }
+}
diff --git a/crates/valgrind/src/lib.rs b/crates/valgrind/src/lib.rs
new file mode 100644
index 0000000000..2c2c37c27b
--- /dev/null
+++ b/crates/valgrind/src/lib.rs
@@ -0,0 +1,101 @@
+#![cfg(test)]
+
+use std::{
+    ffi::OsStr,
+    path::{Path, PathBuf},
+};
+
+use roc_build::{
+    link::{LinkType, LinkingStrategy},
+    program::{CodeGenBackend, CodeGenOptions},
+};
+use roc_cli::build::{BuildOrdering, BuiltFile};
+use roc_load::Threading;
+use roc_mono::ir::OptLevel;
+
+fn list_files(dir: &std::path::Path) -> std::vec::Vec<PathBuf> {
+    std::fs::read_dir(dir)
+        .unwrap()
+        .map(|f| PathBuf::from(f.unwrap().file_name()))
+        .collect::<std::vec::Vec<_>>()
+}
+
+fn run_example(app_module_path: impl AsRef<Path>) {
+    let app_module_path = app_module_path.as_ref();
+
+    let arena = bumpalo::Bump::new();
+    let triple = target_lexicon::Triple::host();
+
+    let code_gen_options = CodeGenOptions {
+        backend: CodeGenBackend::Llvm,
+        opt_level: OptLevel::Normal,
+        emit_debug_info: false,
+    };
+
+    let emit_timings = false;
+    let link_type = LinkType::Executable;
+    let linking_strategy = LinkingStrategy::Surgical;
+    let prebuilt_requested = true;
+    let wasm_dev_stack_bytes = None;
+
+    let roc_cache_dir = roc_packaging::cache::RocCacheDir::Disallowed;
+    let build_ordering = BuildOrdering::AlwaysBuild;
+
+    let res_binary_path = roc_cli::build::build_file(
+        &arena,
+        &triple,
+        PathBuf::from(app_module_path),
+        code_gen_options,
+        emit_timings,
+        link_type,
+        linking_strategy,
+        prebuilt_requested,
+        Threading::AtMost(2),
+        wasm_dev_stack_bytes,
+        roc_cache_dir,
+        build_ordering,
+    );
+
+    match res_binary_path {
+        Ok(BuiltFile {
+            binary_path,
+            problems,
+            total_time: _,
+            expect_metadata: _,
+        }) => {
+            if problems.exit_code() != 0 {
+                panic!("there are problems")
+            }
+            // If possible, report the generated executable name relative to the current dir.
+            let generated_filename = binary_path
+                .strip_prefix(std::env::current_dir().unwrap())
+                .unwrap_or(&binary_path)
+                .to_str()
+                .unwrap();
+
+            let (out, _raw_xml) =
+                cli_utils::helpers::run_with_valgrind([], &[generated_filename.to_string()]);
+
+            if !out.status.success() {
+                panic!(
+                    "Running the application `{:?}` failed!\n\n{}\n\n{}",
+                    out.cmd_str, out.stdout, out.stderr
+                );
+            }
+        }
+        Err(e) => panic!("{:?}", e),
+    }
+}
+
+#[test]
+fn it_works() {
+    for dir_entry in std::fs::read_dir("tests").unwrap() {
+        let path = dir_entry.unwrap().path();
+
+        if path.extension() != Some(OsStr::new("roc")) {
+            continue;
+        }
+
+        run_example(path);
+    }
+}
diff --git a/crates/valgrind/tests/rocLovesZig b/crates/valgrind/tests/rocLovesZig
new file mode 100755
index 0000000000..e57e7f151b
Binary files /dev/null and b/crates/valgrind/tests/rocLovesZig differ
diff --git a/crates/valgrind/tests/str_concat_1.roc b/crates/valgrind/tests/str_concat_1.roc
new file mode 100644
index 0000000000..5424e2bdfb
--- /dev/null
+++ b/crates/valgrind/tests/str_concat_1.roc
@@ -0,0 +1,8 @@
+app "test"
+    packages { pf: "../zig-platform/main.roc" }
+    imports []
+    provides [main] to pf
+
+main =
+    Str.withCapacity 42
+        |> Str.concat "foobar"
diff --git a/crates/valgrind/zig-platform/dynhost b/crates/valgrind/zig-platform/dynhost
new file mode 100755
index 0000000000..9b44a8cc63
Binary files /dev/null and b/crates/valgrind/zig-platform/dynhost differ
diff --git a/crates/valgrind/zig-platform/host.zig b/crates/valgrind/zig-platform/host.zig
new file mode 100644
index 0000000000..7465a1fe0e
--- /dev/null
+++ b/crates/valgrind/zig-platform/host.zig
@@ -0,0 +1,138 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const str = @import("str");
+const RocStr = str.RocStr;
+const testing = std.testing;
+const expectEqual = testing.expectEqual;
+const expect = testing.expect;
+
+comptime {
+    // This is a workaround for https://github.com/ziglang/zig/issues/8218
+    // which is only necessary on macOS.
+    //
+    // Once that issue is fixed, we can undo the changes in
+    // 177cf12e0555147faa4d436e52fc15175c2c4ff0 and go back to passing
+    // -fcompiler-rt in link.rs instead of doing this. Note that this
+    // workaround is present in many host.zig files, so make sure to undo
+    // it everywhere!
+    if (builtin.os.tag == .macos) {
+        _ = @import("compiler_rt");
+    }
+}
+
+const Align = 2 * @alignOf(usize);
+extern fn malloc(size: usize) callconv(.C) ?*align(Align) anyopaque;
+extern fn realloc(c_ptr: [*]align(Align) u8, size: usize) callconv(.C) ?*anyopaque;
+extern fn free(c_ptr: [*]align(Align) u8) callconv(.C) void;
+extern fn memcpy(dst: [*]u8, src: [*]u8, size: usize) callconv(.C) void;
+extern fn memset(dst: [*]u8, value: i32, size: usize) callconv(.C) void;
+
+const DEBUG: bool = false;
+
+export fn roc_alloc(size: usize, alignment: u32) callconv(.C) ?*anyopaque {
+    if (DEBUG) {
+        var ptr = malloc(size);
+        const stdout = std.io.getStdOut().writer();
+        stdout.print("alloc:   {d} (alignment {d}, size {d})\n", .{ ptr, alignment, size }) catch unreachable;
+        return ptr;
+    } else {
+        return malloc(size);
+    }
+}
+
+export fn roc_realloc(c_ptr: *anyopaque, new_size: usize, old_size: usize, alignment: u32) callconv(.C) ?*anyopaque {
+    if (DEBUG) {
+        const stdout = std.io.getStdOut().writer();
+        stdout.print("realloc: {d} (alignment {d}, old_size {d})\n", .{ c_ptr, alignment, old_size }) catch unreachable;
+    }
+
+    return realloc(@alignCast(Align, @ptrCast([*]u8, c_ptr)), new_size);
+}
+
+export fn roc_dealloc(c_ptr: *anyopaque, alignment: u32) callconv(.C) void {
+    if (DEBUG) {
+        const stdout = std.io.getStdOut().writer();
+        stdout.print("dealloc: {d} (alignment {d})\n", .{ c_ptr, alignment }) catch unreachable;
+    }
+
+    free(@alignCast(Align, @ptrCast([*]u8, c_ptr)));
+}
+
+export fn roc_panic(c_ptr: *anyopaque, tag_id: u32) callconv(.C) void {
+    _ = tag_id;
+
+    const stderr = std.io.getStdErr().writer();
+    const msg = @ptrCast([*:0]const u8, c_ptr);
+    stderr.print("Application crashed with message\n\n    {s}\n\nShutting down\n", .{msg}) catch unreachable;
+    std.process.exit(0);
+}
+
+export fn roc_memcpy(dst: [*]u8, src: [*]u8, size: usize) callconv(.C) void {
+    return memcpy(dst, src, size);
+}
+
+export fn roc_memset(dst: [*]u8, value: i32, size: usize) callconv(.C) void {
+    return memset(dst, value, size);
+}
+
+extern fn kill(pid: c_int, sig: c_int) c_int;
+extern fn shm_open(name: *const i8, oflag: c_int, mode: c_uint) c_int;
+extern fn mmap(addr: ?*anyopaque, length: c_uint, prot: c_int, flags: c_int, fd: c_int, offset: c_uint) *anyopaque;
+extern fn getppid() c_int;
+
+fn roc_getppid() callconv(.C) c_int {
+    return getppid();
+}
+
+fn roc_getppid_windows_stub() callconv(.C) c_int {
+    return 0;
+}
+
+fn roc_shm_open(name: *const i8, oflag: c_int, mode: c_uint) callconv(.C) c_int {
+    return shm_open(name, oflag, mode);
+}
+fn roc_mmap(addr: ?*anyopaque, length: c_uint, prot: c_int, flags: c_int, fd: c_int, offset: c_uint) callconv(.C) *anyopaque {
+    return mmap(addr, length, prot, flags, fd, offset);
+}
+
+comptime {
+    if (builtin.os.tag == .macos or builtin.os.tag == .linux) {
+        @export(roc_getppid, .{ .name = "roc_getppid", .linkage = .Strong });
+        @export(roc_mmap, .{ .name = "roc_mmap", .linkage = .Strong });
+        @export(roc_shm_open, .{ .name = "roc_shm_open", .linkage = .Strong });
+    }
+
+    if (builtin.os.tag == .windows) {
+        @export(roc_getppid_windows_stub, .{ .name = "roc_getppid", .linkage = .Strong });
+    }
+}
+
+const mem = std.mem;
+const Allocator = mem.Allocator;
+
+extern fn roc__mainForHost_1_exposed_generic(*RocStr) void;
+
+const Unit = extern struct {};
+
+pub fn main() u8 {
+    const stdout = std.io.getStdOut().writer();
+    const stderr = std.io.getStdErr().writer();
+
+    var timer = std.time.Timer.start() catch unreachable;
+
+    // actually call roc to populate the callresult
+    var callresult = RocStr.empty();
+    roc__mainForHost_1_exposed_generic(&callresult);
+
+    const nanos = timer.read();
+    const seconds = (@intToFloat(f64, nanos) / 1_000_000_000.0);
+
+    // stdout the result
+    stdout.print("{s}", .{callresult.asSlice()}) catch unreachable;
+
+    callresult.deinit();
+
+    stderr.print("runtime: {d:.3}ms\n", .{seconds * 1000}) catch unreachable;
+
+    return 0;
+}
diff --git a/crates/valgrind/zig-platform/libapp.so b/crates/valgrind/zig-platform/libapp.so
new file mode 100644
index 0000000000..ec5fd77dd0
Binary files /dev/null and b/crates/valgrind/zig-platform/libapp.so differ
diff --git a/crates/valgrind/zig-platform/main.roc b/crates/valgrind/zig-platform/main.roc
new file mode 100644
index 0000000000..a52fe9a480
--- /dev/null
+++ b/crates/valgrind/zig-platform/main.roc
@@ -0,0 +1,9 @@
+platform "echo-in-zig"
+    requires {} { main : Str }
+    exposes []
+    packages {}
+    imports []
+    provides [mainForHost]
+
+mainForHost : Str
+mainForHost = main