diff --git a/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp b/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
index 2aed3245507b..d426ba0b01fb 100644
--- a/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
+++ b/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
@@ -432,6 +432,46 @@ ProcessInstruction(MCInst &Inst,
     Inst = TmpInst;
     break;
   }
+  case PPC::SUBI: {
+    MCInst TmpInst;
+    int64_t N = Inst.getOperand(2).getImm();
+    TmpInst.setOpcode(PPC::ADDI);
+    TmpInst.addOperand(Inst.getOperand(0));
+    TmpInst.addOperand(Inst.getOperand(1));
+    TmpInst.addOperand(MCOperand::CreateImm(-N));
+    Inst = TmpInst;
+    break;
+  }
+  case PPC::SUBIS: {
+    MCInst TmpInst;
+    int64_t N = Inst.getOperand(2).getImm();
+    TmpInst.setOpcode(PPC::ADDIS);
+    TmpInst.addOperand(Inst.getOperand(0));
+    TmpInst.addOperand(Inst.getOperand(1));
+    TmpInst.addOperand(MCOperand::CreateImm(-N));
+    Inst = TmpInst;
+    break;
+  }
+  case PPC::SUBIC: {
+    MCInst TmpInst;
+    int64_t N = Inst.getOperand(2).getImm();
+    TmpInst.setOpcode(PPC::ADDIC);
+    TmpInst.addOperand(Inst.getOperand(0));
+    TmpInst.addOperand(Inst.getOperand(1));
+    TmpInst.addOperand(MCOperand::CreateImm(-N));
+    Inst = TmpInst;
+    break;
+  }
+  case PPC::SUBICo: {
+    MCInst TmpInst;
+    int64_t N = Inst.getOperand(2).getImm();
+    TmpInst.setOpcode(PPC::ADDICo);
+    TmpInst.addOperand(Inst.getOperand(0));
+    TmpInst.addOperand(Inst.getOperand(1));
+    TmpInst.addOperand(MCOperand::CreateImm(-N));
+    Inst = TmpInst;
+    break;
+  }
   case PPC::SLWI: {
     MCInst TmpInst;
     int64_t N = Inst.getOperand(2).getImm();
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.td b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
index ee992c03cb92..5b99a66e494d 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
@@ -2276,6 +2276,20 @@ def : InstAlias<"not. $rA, $rB", (NOR8o g8rc:$rA, g8rc:$rB, g8rc:$rB)>;
 
 def LAx : PPCAsmPseudo<"la $rA, $addr", (ins gprc:$rA, memri:$addr)>;
 
+def SUBI : PPCAsmPseudo<"subi $rA, $rB, $imm",
+                        (ins gprc:$rA, gprc:$rB, s16imm:$imm)>;
+def SUBIS : PPCAsmPseudo<"subis $rA, $rB, $imm",
+                         (ins gprc:$rA, gprc:$rB, s16imm:$imm)>;
+def SUBIC : PPCAsmPseudo<"subic $rA, $rB, $imm",
+                         (ins gprc:$rA, gprc:$rB, s16imm:$imm)>;
+def SUBICo : PPCAsmPseudo<"subic. $rA, $rB, $imm",
+                          (ins gprc:$rA, gprc:$rB, s16imm:$imm)>;
+
+def : InstAlias<"sub $rA, $rB, $rC", (SUBF8 g8rc:$rA, g8rc:$rC, g8rc:$rB)>;
+def : InstAlias<"sub. $rA, $rB, $rC", (SUBF8o g8rc:$rA, g8rc:$rC, g8rc:$rB)>;
+def : InstAlias<"subc $rA, $rB, $rC", (SUBFC8 g8rc:$rA, g8rc:$rC, g8rc:$rB)>;
+def : InstAlias<"subc. $rA, $rB, $rC", (SUBFC8o g8rc:$rA, g8rc:$rC, g8rc:$rB)>;
+
 def SLWI : PPCAsmPseudo<"slwi $rA, $rS, $n",
                         (ins gprc:$rA, gprc:$rS, u5imm:$n)>;
 def SRWI : PPCAsmPseudo<"srwi $rA, $rS, $n",
diff --git a/llvm/test/MC/PowerPC/ppc64-encoding-ext.s b/llvm/test/MC/PowerPC/ppc64-encoding-ext.s
index f6bfa6916a7e..a194d1a344fe 100644
--- a/llvm/test/MC/PowerPC/ppc64-encoding-ext.s
+++ b/llvm/test/MC/PowerPC/ppc64-encoding-ext.s
@@ -1788,7 +1788,25 @@
 
 # FIXME: Condition register logical mnemonics
 
-# FIXME: Subtract mnemonics
+# Subtract mnemonics
+
+# CHECK: addi 2, 3, -128                 # encoding: [0x38,0x43,0xff,0x80]
+         subi 2, 3, 128
+# CHECK: addis 2, 3, -128                # encoding: [0x3c,0x43,0xff,0x80]
+         subis 2, 3, 128
+# CHECK: addic 2, 3, -128                # encoding: [0x30,0x43,0xff,0x80]
+         subic 2, 3, 128
+# CHECK: addic. 2, 3, -128               # encoding: [0x34,0x43,0xff,0x80]
+         subic. 2, 3, 128
+
+# CHECK: subf 2, 4, 3                    # encoding: [0x7c,0x44,0x18,0x50]
+         sub 2, 3, 4
+# CHECK: subf. 2, 4, 3                   # encoding: [0x7c,0x44,0x18,0x51]
+         sub. 2, 3, 4
+# CHECK: subfc 2, 4, 3                   # encoding: [0x7c,0x44,0x18,0x10]
+         subc 2, 3, 4
+# CHECK: subfc. 2, 4, 3                  # encoding: [0x7c,0x44,0x18,0x11]
+         subc. 2, 3, 4
 
 # Compare mnemonics