diff --git a/lib/compiler/test_runner.zig b/lib/compiler/test_runner.zig
index 0fd5afad694b6aa417fb7cdfcf7305614574d883..9ecfa4d03951427c9b091f6e59d50c120d4ee7f1 100644
--- a/lib/compiler/test_runner.zig
+++ b/lib/compiler/test_runner.zig
@@ -26,6 +26,7 @@ const runner_threaded_io: Io = Io.Threaded.global_single_threaded.io();
 /// the test runner will communicate with the build runner via `std.zig.Server`.
 const need_simple = switch (builtin.zig_backend) {
     .stage2_aarch64,
+    .stage2_loongarch,
     .stage2_powerpc,
     .stage2_riscv64,
     => true,
diff --git a/lib/std/debug.zig b/lib/std/debug.zig
index 59a8dcd9eae1cf7ba40a1e5e9c50a683186c322c..ca1bf3f6edf8a79fb2459fe481f311ec7f50c4b1 100644
--- a/lib/std/debug.zig
+++ b/lib/std/debug.zig
@@ -498,6 +498,7 @@ threadlocal var panic_stage: usize = 0;
 const use_trap_panic = switch (builtin.zig_backend) {
     .stage2_aarch64,
     .stage2_arm,
+    .stage2_loongarch,
     .stage2_powerpc,
     .stage2_riscv64,
     .stage2_spirv,
diff --git a/lib/std/mem.zig b/lib/std/mem.zig
index 55b9019c4f4d95cfce0f271de52d12a856f9aea8..552dfce320311fb7f672611443de0440a415340b 100644
--- a/lib/std/mem.zig
+++ b/lib/std/mem.zig
@@ -735,6 +735,7 @@ test lessThan {
 const use_vectors = switch (builtin.zig_backend) {
     // These backends don't support vectors yet.
     .stage2_aarch64,
+    .stage2_loongarch,
     .stage2_powerpc,
     .stage2_riscv64,
     => false,
diff --git a/lib/std/os/linux.zig b/lib/std/os/linux.zig
index 8fd3fca48e788610aa574ced6d7c7c56a90c0568..835da881ff859006def9b02fe004fa32df3d2215 100644
--- a/lib/std/os/linux.zig
+++ b/lib/std/os/linux.zig
@@ -681,6 +681,7 @@ pub var elf_aux_maybe: ?[*]std.elf.Auxv = null;
 const extern_getauxval = switch (builtin.zig_backend) {
     // Calling extern functions is not yet supported with these backends
     .stage2_arm,
+    .stage2_loongarch,
     .stage2_powerpc,
     .stage2_riscv64,
     .stage2_sparc64,
diff --git a/lib/std/start.zig b/lib/std/start.zig
index 6021da10325aa38a6be00d59ecc1d58634deba77..20cd8548f711901aa61d64d6799d685512df9521 100644
--- a/lib/std/start.zig
+++ b/lib/std/start.zig
@@ -180,7 +180,10 @@ fn _start() callconv(.naked) noreturn {
             .csky => ".cfi_undefined lr",
             .hexagon => ".cfi_undefined r31",
             .kvx => ".cfi_undefined r14",
-            .loongarch32, .loongarch64 => ".cfi_undefined 1",
+            .loongarch32, .loongarch64 => if (builtin.zig_backend == .stage2_loongarch)
+                ""
+            else
+                ".cfi_undefined 1",
             .m68k => ".cfi_undefined %%pc",
             .m88k => ".cfi_undefined %%r1",
             .microblaze, .microblazeel => "", // No CFI support.
@@ -215,6 +218,32 @@ fn _start() callconv(.naked) noreturn {
     // kernel is usually good about upholding the ABI guarantees, the same cannot be said of dynamic
     // linkers; musl's ldso, for example, opts to not align the stack when invoking the dynamic
     // linker explicitly.
+    if (builtin.zig_backend == .stage2_loongarch) {
+        // TODO: need "X" constraint support
+        asm volatile (switch (native_arch) {
+                .loongarch32 =>
+                \\ move $fp, $zero
+                \\ move $ra, $zero
+                \\ move $a0, $sp
+                \\ srli.w $sp, $sp, 4
+                \\ slli.w $sp, $sp, 4
+                \\ jirl $ra, %[posixCallMainAndExit], 0
+                ,
+                .loongarch64 =>
+                \\ move $fp, $zero
+                \\ move $ra, $zero
+                \\ move $a0, $sp
+                \\ bstrins.d $sp, $zero, 3, 0
+                \\ jirl $ra, %[posixCallMainAndExit], 0
+                ,
+                else => unreachable,
+            }
+            :
+            : [posixCallMainAndExit] "r" (&posixCallMainAndExit),
+            : .{ .r1 = true, .r4 = true, .r22 = true });
+        unreachable;
+    }
+
     asm volatile (switch (native_arch) {
             .x86_64 =>
             \\ xorl %%ebp, %%ebp
diff --git a/lib/std/testing.zig b/lib/std/testing.zig
index eebf3a5195c0d2407c7c51d3b67ef794011f6736..6bef15e8a196bfaf19da01b4eaccff86ee561b15 100644
--- a/lib/std/testing.zig
+++ b/lib/std/testing.zig
@@ -34,6 +34,7 @@ pub var log_level = std.log.Level.warn;
 // Disable printing in tests for simple backends.
 pub const backend_can_print = switch (builtin.zig_backend) {
     .stage2_aarch64,
+    .stage2_loongarch,
     .stage2_powerpc,
     .stage2_riscv64,
     .stage2_spirv,
diff --git a/lib/ubsan_rt.zig b/lib/ubsan_rt.zig
index b6fdc5f5aeedc901213ed96c14710904e6ee6336..8fce8a932bc6843c217dd951938a24f4184ccd4c 100644
--- a/lib/ubsan_rt.zig
+++ b/lib/ubsan_rt.zig
@@ -647,6 +647,7 @@ fn exportHandlerWithAbort(
 }
 
 const can_build_ubsan = switch (builtin.zig_backend) {
+    .stage2_loongarch,
     .stage2_powerpc,
     .stage2_riscv64,
     => false,