Index: lib/Target/Mips/Disassembler/MipsDisassembler.cpp
===================================================================
--- lib/Target/Mips/Disassembler/MipsDisassembler.cpp
+++ lib/Target/Mips/Disassembler/MipsDisassembler.cpp
@@ -555,7 +555,7 @@
   else if (Rs == Rt)
     MI.setOpcode(Mips::BLTZC);
   else
-    return MCDisassembler::Fail; // FIXME: BLTC is not implemented yet.
+    MI.setOpcode(Mips::BLTC);
 
   MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
                                      Rt)));
@@ -595,8 +595,11 @@
   } else if (Rs == Rt) {
     MI.setOpcode(Mips::BLTZALC);
     HasRs = true;
-  } else
-    return MCDisassembler::Fail; // BLTUC not implemented yet
+  } else {
+    MI.setOpcode(Mips::BLTUC);
+    HasRs = true;
+    HasRt = true;
+  }
 
   if (HasRs)
     MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
Index: lib/Target/Mips/Mips32r6InstrInfo.td
===================================================================
--- lib/Target/Mips/Mips32r6InstrInfo.td
+++ lib/Target/Mips/Mips32r6InstrInfo.td
@@ -102,6 +102,11 @@
 class BGTZALC_ENC : CMP_BRANCH_1R_RT_OFF16_FM<OPGROUP_BGTZ>,
                     DecodeDisambiguatedBy<"BgtzGroupBranch">;
 
+class BLTC_ENC  : CMP_BRANCH_2R_OFF16_FM<OPGROUP_BGTZL>,
+                  DecodeDisambiguatedBy<"BgtzlGroupBranch">;
+class BLTUC_ENC : CMP_BRANCH_2R_OFF16_FM<OPGROUP_BGTZ>,
+                  DecodeDisambiguatedBy<"BgtzGroupBranch">;
+
 class BLEZC_ENC : CMP_BRANCH_1R_RT_OFF16_FM<OPGROUP_BLEZL>,
                   DecodeDisambiguatedBy<"BlezlGroupBranch">;
 class BLTZALC_ENC : CMP_BRANCH_1R_BOTH_OFF16_FM<OPGROUP_BGTZ>,
@@ -327,6 +332,9 @@
 class BEQC_DESC : CMP_BC_DESC_BASE<"beqc", brtarget, GPR32Opnd>;
 class BNEC_DESC : CMP_BC_DESC_BASE<"bnec", brtarget, GPR32Opnd>;
 
+class BLTC_DESC : CMP_BC_DESC_BASE<"bltc", brtarget, GPR32Opnd>;
+class BLTUC_DESC : CMP_BC_DESC_BASE<"bltuc", brtarget, GPR32Opnd>;
+
 class BLTZC_DESC : CMP_CBR_RT_Z_DESC_BASE<"bltzc", brtarget, GPR32Opnd>;
 class BGEZC_DESC : CMP_CBR_RT_Z_DESC_BASE<"bgezc", brtarget, GPR32Opnd>;
 
@@ -532,8 +540,8 @@
 def BITSWAP : BITSWAP_ENC, BITSWAP_DESC, ISA_MIPS32R6;
 def BLEZALC : BLEZALC_ENC, BLEZALC_DESC, ISA_MIPS32R6;
 def BLEZC : BLEZC_ENC, BLEZC_DESC, ISA_MIPS32R6;
-def BLTC; // Also aliased to bgtc with operands swapped
-def BLTUC; // Also aliased to bgtuc with operands swapped
+def BLTC : BLTC_ENC, BLTC_DESC, ISA_MIPS32R6;
+def BLTUC : BLTUC_ENC, BLTUC_DESC, ISA_MIPS32R6;
 def BLTZALC : BLTZALC_ENC, BLTZALC_DESC, ISA_MIPS32R6;
 def BLTZC : BLTZC_ENC, BLTZC_DESC, ISA_MIPS32R6;
 def BNEC : BNEC_ENC, BNEC_DESC, ISA_MIPS32R6;
Index: test/MC/Mips/mips32r6/valid.s
===================================================================
--- test/MC/Mips/mips32r6/valid.s
+++ test/MC/Mips/mips32r6/valid.s
@@ -48,6 +48,8 @@
         bgtzc $5, 256            # CHECK: bgtzc $5, 256       # encoding: [0x5c,0x05,0x00,0x40]
         bitswap $4, $2           # CHECK: bitswap $4, $2      # encoding: [0x7c,0x02,0x20,0x20]
         blezalc $2, 1332         # CHECK: blezalc $2, 1332    # encoding: [0x18,0x02,0x01,0x4d]
+        bltc $5, $6, 256         # CHECK: bltc $5, $6, 256    # encoding: [0x5c,0xa6,0x00,0x40]
+        bltuc $5, $6, 256        # CHECK: bltuc $5, $6, 256   # encoding: [0x1c,0xa6,0x00,0x40]
         # bnvc requires that rs >= rt but we accept both. See also bnec
         bnvc     $0, $0, 4       # CHECK: bnvc $zero, $zero, 4 # encoding: [0x60,0x00,0x00,0x01]
         bnvc     $2, $0, 4       # CHECK: bnvc $2, $zero, 4    # encoding: [0x60,0x40,0x00,0x01]
Index: test/MC/Mips/mips64r6/valid.s
===================================================================
--- test/MC/Mips/mips64r6/valid.s
+++ test/MC/Mips/mips64r6/valid.s
@@ -48,6 +48,8 @@
         bgtzc $5, 256            # CHECK: bgtzc $5, 256       # encoding: [0x5c,0x05,0x00,0x40]
         bitswap $4, $2           # CHECK: bitswap $4, $2      # encoding: [0x7c,0x02,0x20,0x20]
         blezalc $2, 1332         # CHECK: blezalc $2, 1332    # encoding: [0x18,0x02,0x01,0x4d]
+        bltc $5, $6, 256         # CHECK: bltc $5, $6, 256    # encoding: [0x5c,0xa6,0x00,0x40]
+        bltuc $5, $6, 256        # CHECK: bltuc $5, $6, 256   # encoding: [0x1c,0xa6,0x00,0x40]
         # bnvc requires that rs >= rt but we accept both. See also bnec
         bnvc     $0, $0, 4       # CHECK: bnvc $zero, $zero, 4 # encoding: [0x60,0x00,0x00,0x01]
         bnvc     $2, $0, 4       # CHECK: bnvc $2, $zero, 4    # encoding: [0x60,0x40,0x00,0x01]