diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2030,6 +2030,14 @@
   const Driver &D = getToolChain().getDriver();
   addX86AlignBranchArgs(D, Args, CmdArgs, /*IsLTO=*/false);
 
+  // 32-bit Solaris/x86 only guarantees 4-byte stack alignment as required by
+  // the i386 psABI, so realign it as necessary for SSE instructions.
+  const llvm::Triple &Triple = getToolChain().getTriple();
+  if (Triple.isOSSolaris() && Triple.getArch() == llvm::Triple::x86 &&
+      Args.hasFlag(options::OPT_mstackrealign, options::OPT_mno_stackrealign,
+                   true))
+    CmdArgs.push_back("-mstackrealign");
+
   if (!Args.hasFlag(options::OPT_mred_zone, options::OPT_mno_red_zone, true) ||
       Args.hasArg(options::OPT_mkernel) ||
       Args.hasArg(options::OPT_fapple_kext))