Index: llvm/trunk/lib/Target/AArch64/AArch64SystemOperands.td
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64SystemOperands.td
+++ llvm/trunk/lib/Target/AArch64/AArch64SystemOperands.td
@@ -108,6 +108,27 @@
 let Requires = [{ {AArch64::FeatureCacheDeepPersist} }] in
 def : DC<"CVADP",  0b011, 0b0111, 0b1101, 0b001>;
 
+let Requires = [{ {AArch64::FeatureMTE} }] in {
+def : DC<"IGVAC",   0b000, 0b0111, 0b0110, 0b011>;
+def : DC<"IGSW",    0b000, 0b0111, 0b0110, 0b100>;
+def : DC<"CGSW",    0b000, 0b0111, 0b1010, 0b100>;
+def : DC<"CIGSW",   0b000, 0b0111, 0b1110, 0b100>;
+def : DC<"CGVAC",   0b011, 0b0111, 0b1010, 0b011>;
+def : DC<"CGVAP",   0b011, 0b0111, 0b1100, 0b011>;
+def : DC<"CGVADP",  0b011, 0b0111, 0b1101, 0b011>;
+def : DC<"CIGVAC",  0b011, 0b0111, 0b1110, 0b011>;
+def : DC<"GVA",     0b011, 0b0111, 0b0100, 0b011>;
+def : DC<"IGDVAC",  0b000, 0b0111, 0b0110, 0b101>;
+def : DC<"IGDSW",   0b000, 0b0111, 0b0110, 0b110>;
+def : DC<"CGDSW",   0b000, 0b0111, 0b1010, 0b110>;
+def : DC<"CIGDSW",  0b000, 0b0111, 0b1110, 0b110>;
+def : DC<"CGDVAC",  0b011, 0b0111, 0b1010, 0b101>;
+def : DC<"CGDVAP",  0b011, 0b0111, 0b1100, 0b101>;
+def : DC<"CGDVADP", 0b011, 0b0111, 0b1101, 0b101>;
+def : DC<"CIGDVAC", 0b011, 0b0111, 0b1110, 0b101>;
+def : DC<"GZVA",    0b011, 0b0111, 0b0100, 0b100>;
+}
+
 //===----------------------------------------------------------------------===//
 // IC (instruction cache maintenance) instruction options.
 //===----------------------------------------------------------------------===//
Index: llvm/trunk/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ llvm/trunk/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
@@ -2825,6 +2825,7 @@
   { "lse", {AArch64::FeatureLSE} },
   { "predctrl", {AArch64::FeaturePredCtrl} },
   { "ccdp", {AArch64::FeatureCacheDeepPersist} },
+  { "mte", {AArch64::FeatureMTE} },
 
   // FIXME: Unsupported extensions
   { "pan", {} },
Index: llvm/trunk/test/MC/AArch64/armv8.5a-mte.s
===================================================================
--- llvm/trunk/test/MC/AArch64/armv8.5a-mte.s
+++ llvm/trunk/test/MC/AArch64/armv8.5a-mte.s
@@ -0,0 +1,60 @@
+// RUN:     llvm-mc -triple aarch64 -show-encoding -mattr=+mte   < %s      | FileCheck %s
+// RUN: not llvm-mc -triple aarch64 -show-encoding -mattr=+v8.5a < %s 2>&1 | FileCheck %s --check-prefix=NOMTE
+// RUN: not llvm-mc -triple aarch64 -show-encoding -mattr=-mte   < %s 2>&1 | FileCheck %s --check-prefix=NOMTE
+
+dc igvac, x0
+dc igsw, x1
+dc cgsw, x2
+dc cigsw, x3
+dc cgvac, x4
+dc cgvap, x5
+dc cgvadp, x6
+dc cigvac, x7
+dc gva, x8
+dc igdvac, x9
+dc igdsw, x10
+dc cgdsw, x11
+dc cigdsw, x12
+dc cgdvac, x13
+dc cgdvap, x14
+dc cgdvadp, x15
+dc cigdvac, x16
+dc gzva, x17
+
+// CHECK: dc igvac, x0          // encoding: [0x60,0x76,0x08,0xd5]
+// CHECK: dc igsw, x1           // encoding: [0x81,0x76,0x08,0xd5]
+// CHECK: dc cgsw, x2           // encoding: [0x82,0x7a,0x08,0xd5]
+// CHECK: dc cigsw, x3          // encoding: [0x83,0x7e,0x08,0xd5]
+// CHECK: dc cgvac, x4          // encoding: [0x64,0x7a,0x0b,0xd5]
+// CHECK: dc cgvap, x5          // encoding: [0x65,0x7c,0x0b,0xd5]
+// CHECK: dc cgvadp, x6         // encoding: [0x66,0x7d,0x0b,0xd5]
+// CHECK: dc cigvac, x7         // encoding: [0x67,0x7e,0x0b,0xd5]
+// CHECK: dc gva, x8            // encoding: [0x68,0x74,0x0b,0xd5]
+// CHECK: dc igdvac, x9         // encoding: [0xa9,0x76,0x08,0xd5]
+// CHECK: dc igdsw, x10         // encoding: [0xca,0x76,0x08,0xd5]
+// CHECK: dc cgdsw, x11         // encoding: [0xcb,0x7a,0x08,0xd5]
+// CHECK: dc cigdsw, x12        // encoding: [0xcc,0x7e,0x08,0xd5]
+// CHECK: dc cgdvac, x13        // encoding: [0xad,0x7a,0x0b,0xd5]
+// CHECK: dc cgdvap, x14        // encoding: [0xae,0x7c,0x0b,0xd5]
+// CHECK: dc cgdvadp, x15       // encoding: [0xaf,0x7d,0x0b,0xd5]
+// CHECK: dc cigdvac, x16       // encoding: [0xb0,0x7e,0x0b,0xd5]
+// CHECK: dc gzva, x17          // encoding: [0x91,0x74,0x0b,0xd5]
+
+// NOMTE: DC IGVAC requires mte
+// NOMTE: DC IGSW requires mte
+// NOMTE: DC CGSW requires mte
+// NOMTE: DC CIGSW requires mte
+// NOMTE: DC CGVAC requires mte
+// NOMTE: DC CGVAP requires mte
+// NOMTE: DC CGVADP requires mte
+// NOMTE: DC CIGVAC requires mte
+// NOMTE: DC GVA requires mte
+// NOMTE: DC IGDVAC requires mte
+// NOMTE: DC IGDSW requires mte
+// NOMTE: DC CGDSW requires mte
+// NOMTE: DC CIGDSW requires mte
+// NOMTE: DC CGDVAC requires mte
+// NOMTE: DC CGDVAP requires mte
+// NOMTE: DC CGDVADP requires mte
+// NOMTE: DC CIGDVAC requires mte
+// NOMTE: DC GZVA requires mte
Index: llvm/trunk/test/MC/Disassembler/AArch64/armv8.5a-mte.txt
===================================================================
--- llvm/trunk/test/MC/Disassembler/AArch64/armv8.5a-mte.txt
+++ llvm/trunk/test/MC/Disassembler/AArch64/armv8.5a-mte.txt
@@ -0,0 +1,60 @@
+# RUN: llvm-mc -triple=aarch64 -mattr=+mte  -disassemble < %s | FileCheck %s
+# RUN: llvm-mc -triple=aarch64 -mattr=+v8.5a -disassemble < %s | FileCheck %s --check-prefix=NOMTE
+# RUN: llvm-mc -triple=aarch64 -mattr=-mte  -disassemble < %s | FileCheck %s --check-prefix=NOMTE
+
+[0x60,0x76,0x08,0xd5]
+[0x81,0x76,0x08,0xd5]
+[0x82,0x7a,0x08,0xd5]
+[0x83,0x7e,0x08,0xd5]
+[0x64,0x7a,0x0b,0xd5]
+[0x65,0x7c,0x0b,0xd5]
+[0x66,0x7d,0x0b,0xd5]
+[0x67,0x7e,0x0b,0xd5]
+[0x68,0x74,0x0b,0xd5]
+[0xa9,0x76,0x08,0xd5]
+[0xca,0x76,0x08,0xd5]
+[0xcb,0x7a,0x08,0xd5]
+[0xcc,0x7e,0x08,0xd5]
+[0xad,0x7a,0x0b,0xd5]
+[0xae,0x7c,0x0b,0xd5]
+[0xaf,0x7d,0x0b,0xd5]
+[0xb0,0x7e,0x0b,0xd5]
+[0x91,0x74,0x0b,0xd5]
+
+# CHECK: dc igvac, x0
+# CHECK: dc igsw, x1
+# CHECK: dc cgsw, x2
+# CHECK: dc cigsw, x3
+# CHECK: dc cgvac, x4
+# CHECK: dc cgvap, x5
+# CHECK: dc cgvadp, x6
+# CHECK: dc cigvac, x7
+# CHECK: dc gva, x8
+# CHECK: dc igdvac, x9
+# CHECK: dc igdsw, x10
+# CHECK: dc cgdsw, x11
+# CHECK: dc cigdsw, x12
+# CHECK: dc cgdvac, x13
+# CHECK: dc cgdvap, x14
+# CHECK: dc cgdvadp, x15
+# CHECK: dc cigdvac, x16
+# CHECK: dc gzva, x17
+
+# NOMTE: sys #0, c7, c6, #3, x0
+# NOMTE: sys #0, c7, c6, #4, x1
+# NOMTE: sys #0, c7, c10, #4, x2
+# NOMTE: sys #0, c7, c14, #4, x3
+# NOMTE: sys #3, c7, c10, #3, x4
+# NOMTE: sys #3, c7, c12, #3, x5
+# NOMTE: sys #3, c7, c13, #3, x6
+# NOMTE: sys #3, c7, c14, #3, x7
+# NOMTE: sys #3, c7, c4, #3, x8
+# NOMTE: sys #0, c7, c6, #5, x9
+# NOMTE: sys #0, c7, c6, #6, x10
+# NOMTE: sys #0, c7, c10, #6, x11
+# NOMTE: sys #0, c7, c14, #6, x12
+# NOMTE: sys #3, c7, c10, #5, x13
+# NOMTE: sys #3, c7, c12, #5, x14
+# NOMTE: sys #3, c7, c13, #5, x15
+# NOMTE: sys #3, c7, c14, #5, x16
+# NOMTE: sys #3, c7, c4, #4, x17