diff --git a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
--- a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
@@ -54,7 +54,8 @@
 
 // Decode AArch64 features from string like +[no]featureA+[no]featureB+...
 static bool DecodeAArch64Features(const Driver &D, StringRef text,
-                                  std::vector<StringRef> &Features) {
+                                  std::vector<StringRef> &Features,
+                                  llvm::AArch64::ArchKind ArchKind) {
   SmallVector<StringRef, 8> Split;
   text.split(Split, StringRef("+"), -1, false);
 
@@ -66,6 +67,10 @@
       D.Diag(clang::diag::err_drv_no_neon_modifier);
     else
       return false;
+
+    // +sve implies +f32mm if the base architecture is v8.6A
+    if ((ArchKind == llvm::AArch64::ArchKind::ARMV8_6A) && Feature == "sve")
+      Features.push_back("+f32mm");
   }
   return true;
 }
@@ -76,6 +81,7 @@
                               std::vector<StringRef> &Features) {
   std::pair<StringRef, StringRef> Split = Mcpu.split("+");
   CPU = Split.first;
+  llvm::AArch64::ArchKind ArchKind = llvm::AArch64::ArchKind::ARMV8A;
 
   if (CPU == "native")
     CPU = llvm::sys::getHostCPUName();
@@ -83,7 +89,7 @@
   if (CPU == "generic") {
     Features.push_back("+neon");
   } else {
-    llvm::AArch64::ArchKind ArchKind = llvm::AArch64::parseCPUArch(CPU);
+    ArchKind = llvm::AArch64::parseCPUArch(CPU);
     if (!llvm::AArch64::getArchFeatures(ArchKind, Features))
       return false;
 
@@ -92,10 +98,11 @@
       return false;
    }
 
-  if (Split.second.size() && !DecodeAArch64Features(D, Split.second, Features))
-    return false;
+   if (Split.second.size() &&
+       !DecodeAArch64Features(D, Split.second, Features, ArchKind))
+     return false;
 
-  return true;
+   return true;
 }
 
 static bool
@@ -108,7 +115,8 @@
   llvm::AArch64::ArchKind ArchKind = llvm::AArch64::parseArch(Split.first);
   if (ArchKind == llvm::AArch64::ArchKind::INVALID ||
       !llvm::AArch64::getArchFeatures(ArchKind, Features) ||
-      (Split.second.size() && !DecodeAArch64Features(D, Split.second, Features)))
+      (Split.second.size() &&
+       !DecodeAArch64Features(D, Split.second, Features, ArchKind)))
     return false;
 
   return true;
diff --git a/clang/test/Driver/aarch64-cpus.c b/clang/test/Driver/aarch64-cpus.c
--- a/clang/test/Driver/aarch64-cpus.c
+++ b/clang/test/Driver/aarch64-cpus.c
@@ -636,6 +636,34 @@
 // RUN: %clang -target aarch64 -march=armv8.5a+bf16+sve -### -c %s 2>&1 | FileCheck -check-prefixes=GENERICV85A-BF16-SVE %s
 // GENERICV85A-BF16-SVE: "-target-feature" "+bf16" "-target-feature" "+sve"
 
+// The 8-bit integer matrix multiply extension is a mandatory component of the
+// Armv8.6-A extensions, but is permitted as an optional feature for any
+// implementation of Armv8.2-A to Armv8.5-A (inclusive)
+// RUN: %clang -target aarch64 -march=armv8.5a -### -c %s 2>&1 | FileCheck -check-prefix=NO-I8MM %s
+// RUN: %clang -target aarch64 -march=armv8.5a+i8mm -### -c %s 2>&1 | FileCheck -check-prefix=I8MM %s
+// NO-I8MM-NOT: "-target-feature" "+i8mm"
+// I8MM: "-target-feature" "+i8mm"
+
+// The 32-bit floating point matrix multiply extension is enabled by default
+// for armv8.6-a targets (or later) with SVE, and can optionally be enabled for
+// any target from armv8.2a onwards (we don't enforce not using it with earlier
+// targets).
+// RUN: %clang -target aarch64 -march=armv8.6a       -### -c %s 2>&1 | FileCheck -check-prefix=NO-F32MM %s
+// RUN: %clang -target aarch64 -march=armv8.6a+sve   -### -c %s 2>&1 | FileCheck -check-prefix=F32MM %s
+// RUN: %clang -target aarch64 -march=armv8.5a+f32mm -### -c %s 2>&1 | FileCheck -check-prefix=F32MM %s
+// NO-F32MM-NOT: "-target-feature" "+f32mm"
+// F32MM: "-target-feature" "+f32mm"
+
+// The 64-bit floating point matrix multiply extension is not currently enabled
+// by default for any targets, because it requires an SVE vector length >= 256
+// bits. When we add a CPU which has that, then it can be enabled by default,
+// but for now it can only be used by adding the +f64mm feature.
+// RUN: %clang -target aarch64 -march=armv8.6a       -### -c %s 2>&1 | FileCheck -check-prefix=NO-F64MM %s
+// RUN: %clang -target aarch64 -march=armv8.6a+sve   -### -c %s 2>&1 | FileCheck -check-prefix=NO-F64MM %s
+// RUN: %clang -target aarch64 -march=armv8.6a+f64mm -### -c %s 2>&1 | FileCheck -check-prefix=F64MM %s
+// NO-F64MM-NOT: "-target-feature" "+f64mm"
+// F64MM: "-target-feature" "+f64mm"
+
 // fullfp16 is off by default for v8a, feature must not be mentioned
 // RUN: %clang -target aarch64 -march=armv8a  -### -c %s 2>&1 | FileCheck -check-prefix=V82ANOFP16 -check-prefix=GENERIC %s
 // RUN: %clang -target aarch64 -march=armv8-a -### -c %s 2>&1 | FileCheck -check-prefix=V82ANOFP16 -check-prefix=GENERIC %s
diff --git a/clang/test/Driver/arm-matrix-multiply.c b/clang/test/Driver/arm-matrix-multiply.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/arm-matrix-multiply.c
@@ -0,0 +1,14 @@
+// RUN: %clang -### -target arm-none-none-eabi -march=armv8.5a+i8mm %s 2>&1 | FileCheck %s
+// RUN: %clang -### -target aarch64-none-none-eabi -march=armv8.5a+i8mm %s 2>&1 | FileCheck %s
+// CHECK: "-target-feature" "+i8mm"
+// CHECK-NOT: "-target-feature" "-i8mm"
+
+// RUN: %clang -### -target arm-none-none-eabi -march=armv8.6a+noi8mm %s 2>&1 | FileCheck %s --check-prefix=NOI8MM
+// RUN: %clang -### -target aarch64-none-none-eabi -march=armv8.6a+noi8mm %s 2>&1 | FileCheck %s --check-prefix=NOI8MM
+// NOI8MM: "-target-feature" "-i8mm"
+// NOI8MM-NOT: "-target-feature" "+i8mm"
+
+// RUN: %clang -### -target arm-none-none-eabi %s 2>&1 | FileCheck %s --check-prefix=ABSENT
+// RUN: %clang -### -target aarch64-none-none-eabi %s 2>&1 | FileCheck %s --check-prefix=ABSENT
+// ABSENT-NOT: "-target-feature" "+i8mm"
+// ABSENT-NOT: "-target-feature" "-i8mm"
diff --git a/llvm/include/llvm/Support/AArch64TargetParser.h b/llvm/include/llvm/Support/AArch64TargetParser.h
--- a/llvm/include/llvm/Support/AArch64TargetParser.h
+++ b/llvm/include/llvm/Support/AArch64TargetParser.h
@@ -24,7 +24,7 @@
 namespace AArch64 {
 
 // Arch extension modifiers for CPUs.
-enum ArchExtKind : unsigned {
+enum ArchExtKind : uint64_t {
   AEK_INVALID =     0,
   AEK_NONE =        1,
   AEK_CRC =         1 << 1,
@@ -57,6 +57,8 @@
   AEK_TME =         1 << 28,
   AEK_BF16 =        1 << 29,
   AEK_I8MM =        1 << 30,
+  AEK_F32MM =       1ULL << 31,
+  AEK_F64MM =       1ULL << 32,
 };
 
 enum class ArchKind {
diff --git a/llvm/include/llvm/Support/AArch64TargetParser.def b/llvm/include/llvm/Support/AArch64TargetParser.def
--- a/llvm/include/llvm/Support/AArch64TargetParser.def
+++ b/llvm/include/llvm/Support/AArch64TargetParser.def
@@ -88,6 +88,8 @@
 AARCH64_ARCH_EXT_NAME("predres",      AArch64::AEK_PREDRES,     "+predres", "-predres")
 AARCH64_ARCH_EXT_NAME("bf16",         AArch64::AEK_BF16,        "+bf16",  "-bf16")
 AARCH64_ARCH_EXT_NAME("i8mm",         AArch64::AEK_I8MM,        "+i8mm",  "-i8mm")
+AARCH64_ARCH_EXT_NAME("f32mm",        AArch64::AEK_F32MM,       "+f32mm", "-f32mm")
+AARCH64_ARCH_EXT_NAME("f64mm",        AArch64::AEK_F64MM,       "+f64mm", "-f64mm")
 AARCH64_ARCH_EXT_NAME("tme",          AArch64::AEK_TME,         "+tme",   "-tme")
 #undef AARCH64_ARCH_EXT_NAME
 
diff --git a/llvm/include/llvm/Support/ARMTargetParser.h b/llvm/include/llvm/Support/ARMTargetParser.h
--- a/llvm/include/llvm/Support/ARMTargetParser.h
+++ b/llvm/include/llvm/Support/ARMTargetParser.h
@@ -47,14 +47,15 @@
   AEK_FP_DP   =     1 << 18,
   AEK_LOB     =     1 << 19,
   AEK_BF16    =     1 << 20,
-  AEK_CDECP0 =      1 << 21,
-  AEK_CDECP1 =      1 << 22,
-  AEK_CDECP2 =      1 << 23,
-  AEK_CDECP3 =      1 << 24,
-  AEK_CDECP4 =      1 << 25,
-  AEK_CDECP5 =      1 << 26,
-  AEK_CDECP6 =      1 << 27,
-  AEK_CDECP7 =      1 << 28,
+  AEK_I8MM    =     1 << 21,
+  AEK_CDECP0 =      1 << 22,
+  AEK_CDECP1 =      1 << 23,
+  AEK_CDECP2 =      1 << 24,
+  AEK_CDECP3 =      1 << 25,
+  AEK_CDECP4 =      1 << 26,
+  AEK_CDECP5 =      1 << 27,
+  AEK_CDECP6 =      1 << 28,
+  AEK_CDECP7 =      1 << 29,
 
   // Unsupported extensions.
   AEK_OS       =    1ULL << 59,
diff --git a/llvm/include/llvm/Support/ARMTargetParser.def b/llvm/include/llvm/Support/ARMTargetParser.def
--- a/llvm/include/llvm/Support/ARMTargetParser.def
+++ b/llvm/include/llvm/Support/ARMTargetParser.def
@@ -116,7 +116,8 @@
          ARMBuildAttrs::CPUArch::v8_A, FK_CRYPTO_NEON_FP_ARMV8,
          (ARM::AEK_SEC        | ARM::AEK_MP   | ARM::AEK_VIRT | ARM::AEK_HWDIVARM |
           ARM::AEK_HWDIVTHUMB | ARM::AEK_DSP  | ARM::AEK_CRC  | ARM::AEK_RAS |
-          ARM::AEK_DOTPROD    | ARM::AEK_BF16 | ARM::AEK_SHA2 | ARM::AEK_AES))
+          ARM::AEK_DOTPROD    | ARM::AEK_BF16 | ARM::AEK_SHA2 | ARM::AEK_AES |
+          ARM::AEK_I8MM))
 ARM_ARCH("armv8-r", ARMV8R, "8-R", "v8r", ARMBuildAttrs::CPUArch::v8_R,
           FK_NEON_FP_ARMV8,
           (ARM::AEK_MP | ARM::AEK_VIRT | ARM::AEK_HWDIVARM | ARM::AEK_HWDIVTHUMB |
@@ -171,6 +172,7 @@
 ARM_ARCH_EXT_NAME("fp16fml",  ARM::AEK_FP16FML,  "+fp16fml", "-fp16fml")
 ARM_ARCH_EXT_NAME("bf16",     ARM::AEK_BF16,     "+bf16",    "-bf16")
 ARM_ARCH_EXT_NAME("sb",       ARM::AEK_SB,       "+sb",      "-sb")
+ARM_ARCH_EXT_NAME("i8mm",     ARM::AEK_I8MM,     "+i8mm",    "-i8mm")
 ARM_ARCH_EXT_NAME("lob",      ARM::AEK_LOB,      "+lob",   "-lob")
 ARM_ARCH_EXT_NAME("cdecp0",   ARM::AEK_CDECP0,   "+cdecp0",  "-cdecp0")
 ARM_ARCH_EXT_NAME("cdecp1",   ARM::AEK_CDECP1,   "+cdecp1",  "-cdecp1")
diff --git a/llvm/unittests/Support/TargetParserTest.cpp b/llvm/unittests/Support/TargetParserTest.cpp
--- a/llvm/unittests/Support/TargetParserTest.cpp
+++ b/llvm/unittests/Support/TargetParserTest.cpp
@@ -636,6 +636,7 @@
                               {"maverick", "maverick", nullptr, nullptr},
                               {"xscale", "noxscale", nullptr, nullptr},
                               {"sb", "nosb", "+sb", "-sb"},
+                              {"i8mm", "noi8mm", "+i8mm", "-i8mm"},
                               {"mve", "nomve", "+mve", "-mve"},
                               {"mve.fp", "nomve.fp", "+mve.fp", "-mve.fp"}};
 
@@ -1230,7 +1231,10 @@
                               {"tme", "notme", "+tme", "-tme"},
                               {"ssbs", "nossbs", "+ssbs", "-ssbs"},
                               {"sb", "nosb", "+sb", "-sb"},
-                              {"predres", "nopredres", "+predres", "-predres"}
+                              {"predres", "nopredres", "+predres", "-predres"},
+                              {"i8mm", "noi8mm", "+i8mm", "-i8mm"},
+                              {"f32mm", "nof32mm", "+f32mm", "-f32mm"},
+                              {"f64mm", "nof64mm", "+f64mm", "-f64mm"},
 };
 
   for (unsigned i = 0; i < array_lengthof(ArchExt); i++) {