Index: lib/Target/Mips/Mips64InstrInfo.td
===================================================================
--- lib/Target/Mips/Mips64InstrInfo.td
+++ lib/Target/Mips/Mips64InstrInfo.td
@@ -455,9 +455,6 @@
 def : MipsInstAlias<"add $rs, $imm",
                     (ADDi GPR32Opnd:$rs, GPR32Opnd:$rs, simm16:$imm),
                     0>;
-def : MipsInstAlias<"addu $rs, $imm",
-                    (ADDiu GPR32Opnd:$rs, GPR32Opnd:$rs, simm16:$imm),
-                    0>;
 def : MipsInstAlias<"dsll $rd, $rt, $rs",
                     (DSLLV GPR64Opnd:$rd, GPR64Opnd:$rt, GPR32Opnd:$rs), 0>,
                     ISA_MIPS3;
Index: lib/Target/Mips/MipsInstrInfo.td
===================================================================
--- lib/Target/Mips/MipsInstrInfo.td
+++ lib/Target/Mips/MipsInstrInfo.td
@@ -1436,6 +1436,8 @@
       ISA_MIPS1_NOT_32R6_64R6;
 def : MipsInstAlias<"addu $rs, $rt, $imm",
                     (ADDiu GPR32Opnd:$rs, GPR32Opnd:$rt, simm16:$imm), 0>;
+def : MipsInstAlias<"addu $rs, $imm",
+                    (ADDiu GPR32Opnd:$rs, GPR32Opnd:$rs, simm16:$imm), 0>;
 def : MipsInstAlias<"add $rs, $rt, $imm",
                     (ADDi GPR32Opnd:$rs, GPR32Opnd:$rt, simm16:$imm), 0>;
 def : MipsInstAlias<"and $rs, $rt, $imm",
Index: test/MC/Mips/mips1/valid.s
===================================================================
--- test/MC/Mips/mips1/valid.s
+++ test/MC/Mips/mips1/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips2/valid.s
===================================================================
--- test/MC/Mips/mips2/valid.s
+++ test/MC/Mips/mips2/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips3/valid.s
===================================================================
--- test/MC/Mips/mips3/valid.s
+++ test/MC/Mips/mips3/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips32/valid.s
===================================================================
--- test/MC/Mips/mips32/valid.s
+++ test/MC/Mips/mips32/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips32r2/valid.s
===================================================================
--- test/MC/Mips/mips32r2/valid.s
+++ test/MC/Mips/mips32r2/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips32r6/valid.s
===================================================================
--- test/MC/Mips/mips32r6/valid.s
+++ test/MC/Mips/mips32r6/valid.s
@@ -17,6 +17,7 @@
         # FIXME: Add the instructions carried forward from older ISA's
         and     $2,4             # CHECK: andi $2, $2, 4      # encoding: [0x30,0x42,0x00,0x04]
         addiupc $4, 100          # CHECK: addiupc $4, 100     # encoding: [0xec,0x80,0x00,0x19]
+        addu    $9,10            # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         align   $4, $2, $3, 2    # CHECK: align $4, $2, $3, 2 # encoding: [0x7c,0x43,0x22,0xa0]
         aluipc  $3, 56           # CHECK: aluipc $3, 56       # encoding: [0xec,0x7f,0x00,0x38]
         aui     $3,$2,-23        # CHECK: aui $3, $2, -23     # encoding: [0x3c,0x62,0xff,0xe9]
Index: test/MC/Mips/mips4/valid.s
===================================================================
--- test/MC/Mips/mips4/valid.s
+++ test/MC/Mips/mips4/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips5/valid.s
===================================================================
--- test/MC/Mips/mips5/valid.s
+++ test/MC/Mips/mips5/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips64/valid.s
===================================================================
--- test/MC/Mips/mips64/valid.s
+++ test/MC/Mips/mips64/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips64r2/valid.s
===================================================================
--- test/MC/Mips/mips64r2/valid.s
+++ test/MC/Mips/mips64r2/valid.s
@@ -11,6 +11,7 @@
         addi      $13,$9,26322
         addi      $8,$8,~1             # CHECK: addi $8, $8, -2 # encoding: [0x21,0x08,0xff,0xfe]
         addu      $9,$a0,$a2
+        addu      $9,10                # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         and       $s7,$v0,$12
         and       $2,4                 # CHECK: andi $2, $2, 4 # encoding: [0x30,0x42,0x00,0x04]
         bc1f      $fcc0, 4             # CHECK: bc1f 4        # encoding: [0x45,0x00,0x00,0x01]
Index: test/MC/Mips/mips64r6/valid.s
===================================================================
--- test/MC/Mips/mips64r6/valid.s
+++ test/MC/Mips/mips64r6/valid.s
@@ -17,6 +17,7 @@
         # FIXME: Add the instructions carried forward from older ISA's
         and     $2,4           # CHECK: andi $2, $2, 4        # encoding: [0x30,0x42,0x00,0x04]
         addiupc $4, 100          # CHECK: addiupc $4, 100     # encoding: [0xec,0x80,0x00,0x19]
+        addu    $9,10            # CHECK: addiu $9, $9, 10    # encoding: [0x25,0x29,0x00,0x0a]
         align   $4, $2, $3, 2    # CHECK: align $4, $2, $3, 2 # encoding: [0x7c,0x43,0x22,0xa0]
         aluipc  $3, 56           # CHECK: aluipc $3, 56       # encoding: [0xec,0x7f,0x00,0x38]
         aui     $3,$2,-23        # CHECK: aui $3, $2, -23     # encoding: [0x3c,0x62,0xff,0xe9]