Upstream-Bug: https://codeberg.org/ziglang/zig/issues/36919
Patch-Author: https://codeberg.org/mganguin

--- a/lib/std/zig/LibCInstallation.zig
+++ b/lib/std/zig/LibCInstallation.zig
@@ -24,6 +24,8 @@ msvc_lib_dir: ?[]const u8 = null,
 kernel32_lib_dir: ?[]const u8 = null,
 cc_dir: ?[]const u8 = null,
 darwin_sdk_dir: ?[]const u8 = null,
+crtbegin_obj: ?[]const u8 = null,
+crtend_obj: ?[]const u8 = null,
 
 pub const FindError = error{
     OutOfMemory,
@@ -147,6 +149,11 @@ pub fn render(self: LibCInstallation, out: *std.Io.Writer) !void {
         \\# Only needed when targeting Haiku, Linux, or SerenityOS.
         \\cc_dir={s}
         \\
+        \\# Define these if the crtbegin/end files are not named `crtbegin.o` and `crtend.o`
+        \\# Only needed when using LLVM compiler-rt versions `clang_rt.crtbegin-x86_64.o`
+        \\crtbegin_obj={s}
+        \\crtend_obj={s}
+        \\
         \\# The directory that contains `crt1.o` or `crt2.o`.
         \\# On POSIX, can be found with `cc -print-file-name=crt1.o`.
         \\crt_dir={s}
@@ -167,6 +174,8 @@ pub fn render(self: LibCInstallation, out: *std.Io.Writer) !void {
         self.include_dir orelse "",
         self.sys_include_dir orelse "",
         self.cc_dir orelse "",
+        self.crtbegin_obj orelse "",
+        self.crtend_obj orelse "",
         self.crt_dir orelse "",
         self.msvc_lib_dir orelse "",
         self.kernel32_lib_dir orelse "",
@@ -469,12 +478,25 @@ fn findNativeCrtDirPosix(self: *LibCInstallation, gpa: Allocator, io: Io, args:
 }
 
 fn findNativeGccDirPosix(self: *LibCInstallation, gpa: Allocator, io: Io, args: FindNativeOptions) FindError!void {
-    self.cc_dir = try ccPrintFileName(gpa, io, .{
+    self.cc_dir = ccPrintFileName(gpa, io, .{
         .environ_map = args.environ_map,
         .search_basename = "crtbeginS.o",
         .want_dirname = .only_dir,
         .verbose = args.verbose,
-    });
+    }) catch |err| switch (err) {
+        error.LibCRuntimeNotFound => blk: {
+            // crtbeginS.o not found, try again with LLVM compiler-rt crtbegin
+            self.crtbegin_obj = try gpa.print("clang_rt.crtbegin-{s}.o", .{@tagName(args.target.cpu.arch)});
+            self.crtend_obj = try gpa.print("clang_rt.crtend-{s}.o", .{@tagName(args.target.cpu.arch)});
+            break :blk try ccPrintFileName(gpa, io, .{
+                .environ_map = args.environ_map,
+                .search_basename = self.crtbegin_obj.?,
+                .want_dirname = .only_dir,
+                .verbose = args.verbose,
+            });
+        },
+        else => return err,
+    };
 }
 
 fn findNativeKernel32LibDir(
@@ -1036,11 +1058,16 @@ pub fn resolveCrtPaths(
                 .root_dir = Cache.Directory.cwd(),
                 .sub_path = lci.cc_dir orelse return error.LibCInstallationMissingCcDir,
             };
+
+            // LLVM compiler-rt has only one version of crtbegin, regardless of link_mode
+            const crtbegin = lci.crtbegin_obj orelse crt_basenames.crtbegin;
+            const crtend = lci.crtend_obj orelse crt_basenames.crtend;
+
             return .{
                 .crt0 = if (crt_basenames.crt0) |basename| try crt_dir_path.join(arena, basename) else null,
                 .crti = if (crt_basenames.crti) |basename| try crt_dir_path.join(arena, basename) else null,
-                .crtbegin = if (crt_basenames.crtbegin) |basename| try cc_dir_path.join(arena, basename) else null,
-                .crtend = if (crt_basenames.crtend) |basename| try cc_dir_path.join(arena, basename) else null,
+                .crtbegin = if (crtbegin) |basename| try cc_dir_path.join(arena, basename) else null,
+                .crtend = if (crtend) |basename| try cc_dir_path.join(arena, basename) else null,
                 .crtn = if (crt_basenames.crtn) |basename| try crt_dir_path.join(arena, basename) else null,
             };
         },