diff --git a/lib/std/c.zig b/lib/std/c.zig
index 9d9c7c5708ef..cc7bd17cb06d 100644
--- a/lib/std/c.zig
+++ b/lib/std/c.zig
@@ -2528,6 +2528,8 @@ pub const _SC = if (builtin.abi.isAndroid()) enum(c_int) {
     .solaris, .illumos => enum(c_int) {
         PAGESIZE = 11,
         NPROCESSORS_ONLN = 15,
+        SIGRT_MIN = 40,
+        SIGRT_MAX = 41,
     },
     // https://github.com/SerenityOS/serenity/blob/1dfc9e2df39dd23f1de92530677c845aae4345f2/Kernel/API/POSIX/unistd.h#L36-L52
     .serenity => enum(c_int) {
@@ -5776,6 +5778,20 @@ pub const MSG = switch (native_os) {
         pub const FBLOCKING = 0x10000;
         pub const FNONBLOCKING = 0x20000;
     },
+    .solaris, .illumos => struct {
+        pub const OOB = 0x0001;
+        pub const PEEK = 0x0002;
+        pub const DONTROUTE = 0x0004;
+        pub const EOR = 0x0008;
+        pub const CTRUNC = 0x0010;
+        pub const TRUNC = 0x0020;
+        pub const WAITALL = 0x0040;
+        pub const DONTWAIT = 0x0080;
+        pub const NOTIFICATION = 0x0100;
+        pub const NOSIGNAL = 0x0200;
+        pub const CMSG_CLOEXEC = 0x1000;
+        pub const CMSG_CLOFORK = 0x2000;
+    },
     else => void,
 };
 pub const SOCK = switch (native_os) {
@@ -10298,7 +10314,7 @@ pub extern "c" fn setrlimit64(resource: rlimit_resource, rlim: *const rlimit) c_
 
 pub const arc4random_buf = switch (native_os) {
     .linux => if (builtin.abi.isAndroid()) private.arc4random_buf else {},
-    .dragonfly, .netbsd, .freebsd, .solaris, .openbsd, .serenity, .macos, .ios, .tvos, .watchos, .visionos => private.arc4random_buf,
+    .dragonfly, .netbsd, .freebsd, .solaris, .illumos, .openbsd, .serenity, .macos, .ios, .tvos, .watchos, .visionos => private.arc4random_buf,
     else => {},
 };
 pub const getentropy = switch (native_os) {
@@ -10475,6 +10491,7 @@ pub fn sigrtmin() u8 {
     return switch (native_os) {
         .freebsd => 65,
         .netbsd => 33,
+        .solaris, .illumos => @truncate(sysconf(@intFromEnum(_SC.SIGRT_MIN))),
         else => @truncate(@as(c_uint, @bitCast(private.__libc_current_sigrtmin()))),
     };
 }
@@ -10484,6 +10501,7 @@ pub fn sigrtmax() u8 {
     return switch (native_os) {
         .freebsd => 126,
         .netbsd => 63,
+        .solaris, .illumos => @truncate(sysconf(@intFromEnum(_SC.SIGRT_MAX))),
         else => @truncate(@as(c_uint, @bitCast(private.__libc_current_sigrtmax()))),
     };
 }
diff --git a/lib/std/debug/cpu_context.zig b/lib/std/debug/cpu_context.zig
index 1ff61ee2a25e..bf1edd83c84a 100644
--- a/lib/std/debug/cpu_context.zig
+++ b/lib/std/debug/cpu_context.zig
@@ -1963,6 +1963,9 @@ const signal_ucontext_t = switch (native_os) {
                 _trapno: i64,
                 _err: i64,
                 rip: u64,
+                _cs: i64,
+                _rflags: i64,
+                rsp: u64,
             },
         },
         else => unreachable,
@@ -2012,6 +2015,9 @@ const signal_ucontext_t = switch (native_os) {
                 _trapno: i64,
                 _err: i64,
                 rip: u64,
+                _cs: i64,
+                _rflags: i64,
+                rsp: u64,
             },
             else => unreachable,
         },
diff --git a/src/target.zig b/src/target.zig
index f878f8e6bc31..79e647e641b4 100644
--- a/src/target.zig
+++ b/src/target.zig
@@ -257,6 +257,10 @@ pub fn hasNewLinkerSupport(ofmt: std.Target.ObjectFormat, backend: std.builtin.C
 pub fn selfHostedBackendIsAsRobustAsLlvm(target: *const std.Target) bool {
     if (target.cpu.arch.isSpirV()) return true;
     if (target.cpu.arch == .x86_64 and target.ptrBitWidth() == 64) {
+        if (target.os.tag.isSolarish()) {
+            // https://github.com/ziglang/zig/issues/25699
+            return false;
+        }
         if (target.os.tag.isBSD()) {
             // Self-hosted linker needs work: https://github.com/ziglang/zig/issues/24341
             return false;
diff --git a/test/src/ErrorTrace.zig b/test/src/ErrorTrace.zig
index 4644661205be..3c781e3a3a88 100644
--- a/test/src/ErrorTrace.zig
+++ b/test/src/ErrorTrace.zig
@@ -41,7 +41,7 @@ pub fn addCase(self: *ErrorTrace, case: Case) void {
 fn shouldTestNonLlvm(target: *const std.Target) bool {
     return switch (target.cpu.arch) {
         .x86_64 => switch (target.ofmt) {
-            .elf => !target.os.tag.isBSD(),
+            .elf => !target.os.tag.isBSD() and !target.os.tag.isSolarish(),
             else => false,
         },
         else => false,
diff --git a/test/src/StackTrace.zig b/test/src/StackTrace.zig
index f6198935fdce..721db139c2d4 100644
--- a/test/src/StackTrace.zig
+++ b/test/src/StackTrace.zig
@@ -46,7 +46,7 @@ fn addCaseTarget(
 ) void {
     const both_backends = switch (target.result.cpu.arch) {
         .x86_64 => switch (target.result.ofmt) {
-            .elf => !target.result.os.tag.isBSD(),
+            .elf => !target.result.os.tag.isBSD() and !target.result.os.tag.isSolarish(),
             else => false,
         },
         else => false,
diff --git a/test/tests.zig b/test/tests.zig
index c7fe8a7e7885..d83c95956a45 100644
--- a/test/tests.zig
+++ b/test/tests.zig
@@ -2493,7 +2493,7 @@ pub fn wouldUseLlvm(use_llvm: ?bool, query: std.Target.Query, optimize_mode: Opt
     const cpu_arch = query.cpu_arch orelse builtin.cpu.arch;
     const os_tag = query.os_tag orelse builtin.os.tag;
     switch (cpu_arch) {
-        .x86_64 => if (os_tag.isBSD() or std.Target.ptrBitWidth_arch_abi(cpu_arch, query.abi orelse .none) != 64) return true,
+        .x86_64 => if (os_tag.isBSD() or os_tag.isSolarish() or std.Target.ptrBitWidth_arch_abi(cpu_arch, query.abi orelse .none) != 64) return true,
         .spirv32, .spirv64 => return false,
         else => return true,
     }