Index: llvm/lib/Target/RISCV/RISCVSystemOperands.td
===================================================================
--- llvm/lib/Target/RISCV/RISCVSystemOperands.td
+++ llvm/lib/Target/RISCV/RISCVSystemOperands.td
@@ -310,6 +310,9 @@
 //===--------------------------
 // Machine Counter Setup
 //===--------------------------
+def : SysReg<"mcountinhibit", 0x320> {
+  let AltName = "mucounteren";
+}
 def : SysReg<"mhpmevent3", 0x323>;
 def : SysReg<"mhpmevent4", 0x324>;
 def : SysReg<"mhpmevent5", 0x325>;
Index: llvm/test/MC/RISCV/machine-csr-names.s
===================================================================
--- llvm/test/MC/RISCV/machine-csr-names.s
+++ llvm/test/MC/RISCV/machine-csr-names.s
@@ -849,6 +849,34 @@
 ######################################
 # Machine Counter Setup
 ######################################
+# mcountinhibit
+# name
+# CHECK-INST: csrrs t1, mcountinhibit, zero
+# CHECK-ENC:  encoding: [0x73,0x23,0x00,0x32]
+# CHECK-INST-ALIAS: csrr t1, mcountinhibit
+# uimm12
+# CHECK-INST: csrrs t2, mcountinhibit, zero
+# CHECK-ENC:  encoding: [0xf3,0x23,0x00,0x32]
+# CHECK-INST-ALIAS: csrr t2, mcountinhibit
+# name
+csrrs t1, mcountinhibit, zero
+# uimm12
+csrrs t2, 0x320, zero
+
+# mucounteren
+# name
+# CHECK-INST: csrrs t1, mcountinhibit, zero
+# CHECK-ENC:  encoding: [0x73,0x23,0x00,0x32]
+# CHECK-INST-ALIAS: csrr t1, mcountinhibit
+# uimm12
+# CHECK-INST: csrrs t2, mcountinhibit, zero
+# CHECK-ENC:  encoding: [0xf3,0x23,0x00,0x32]
+# CHECK-INST-ALIAS: csrr t2, mcountinhibit
+# name
+csrrs t1, mucounteren, zero
+# uimm12
+csrrs t2, 0x320, zero
+
 # mhpmevent3
 # name
 # CHECK-INST: csrrs t1, mhpmevent3, zero