diff --git a/llvm/lib/Target/Sparc/SparcInstrAliases.td b/llvm/lib/Target/Sparc/SparcInstrAliases.td
--- a/llvm/lib/Target/Sparc/SparcInstrAliases.td
+++ b/llvm/lib/Target/Sparc/SparcInstrAliases.td
@@ -491,6 +491,7 @@
 
 def : MnemonicAlias<"stuha", "stha">;
 def : MnemonicAlias<"stsha", "stha">;
+def : MnemonicAlias<"stw", "st">, Requires<[HasV9]>;
 
 def : MnemonicAlias<"lduw", "ld">, Requires<[HasV9]>;
 def : MnemonicAlias<"lduwa", "lda">, Requires<[HasV9]>;
diff --git a/llvm/test/MC/Sparc/sparcv9-instructions.s b/llvm/test/MC/Sparc/sparcv9-instructions.s
--- a/llvm/test/MC/Sparc/sparcv9-instructions.s
+++ b/llvm/test/MC/Sparc/sparcv9-instructions.s
@@ -293,3 +293,6 @@
         ! V8-NEXT: rdpr %wstate,%i5
         ! V9: rdpr %wstate, %i5         ! encoding: [0xbb,0x53,0x80,0x00]
         rdpr %wstate,%i5
+
+        ! V9: st %o1, [%o0]             ! encoding: [0xd2,0x22,0x00,0x00]
+        stw %o1, [%o0]