diff --git a/llvm/lib/Target/RISCV/RISCVInstrFormats.td b/llvm/lib/Target/RISCV/RISCVInstrFormats.td
--- a/llvm/lib/Target/RISCV/RISCVInstrFormats.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrFormats.td
@@ -125,12 +125,14 @@
 }
 def OPC_LOAD      : RISCVOpcode<"LOAD",      0b0000011>;
 def OPC_LOAD_FP   : RISCVOpcode<"LOAD_FP",   0b0000111>;
+def OPC_CUSTOM_0  : RISCVOpcode<"CUSTOM_0",  0b0001011>;
 def OPC_MISC_MEM  : RISCVOpcode<"MISC_MEM",  0b0001111>;
 def OPC_OP_IMM    : RISCVOpcode<"OP_IMM",    0b0010011>;
 def OPC_AUIPC     : RISCVOpcode<"AUIPC",     0b0010111>;
 def OPC_OP_IMM_32 : RISCVOpcode<"OP_IMM_32", 0b0011011>;
 def OPC_STORE     : RISCVOpcode<"STORE",     0b0100011>;
 def OPC_STORE_FP  : RISCVOpcode<"STORE_FP",  0b0100111>;
+def OPC_CUSTOM_1  : RISCVOpcode<"CUSTOM_1",  0b0101011>;
 def OPC_AMO       : RISCVOpcode<"AMO",       0b0101111>;
 def OPC_OP        : RISCVOpcode<"OP",        0b0110011>;
 def OPC_LUI       : RISCVOpcode<"LUI",       0b0110111>;
@@ -141,10 +143,12 @@
 def OPC_NMADD     : RISCVOpcode<"NMADD",     0b1001111>;
 def OPC_OP_FP     : RISCVOpcode<"OP_FP",     0b1010011>;
 def OPC_OP_V      : RISCVOpcode<"OP_V",      0b1010111>;
+def OPC_CUSTOM_2  : RISCVOpcode<"CUSTOM_2",  0b1011011>;
 def OPC_BRANCH    : RISCVOpcode<"BRANCH",    0b1100011>;
 def OPC_JALR      : RISCVOpcode<"JALR",      0b1100111>;
 def OPC_JAL       : RISCVOpcode<"JAL",       0b1101111>;
 def OPC_SYSTEM    : RISCVOpcode<"SYSTEM",    0b1110011>;
+def OPC_CUSTOM_3  : RISCVOpcode<"CUSTOM_3",  0b1111011>;
 
 class RVInst<dag outs, dag ins, string opcodestr, string argstr,
              list<dag> pattern, InstFormat format>