Index: clang/test/CodeGen/arm-target-features.c
===================================================================
--- clang/test/CodeGen/arm-target-features.c
+++ clang/test/CodeGen/arm-target-features.c
@@ -107,4 +107,7 @@
 // RUN: %clang_cc1 -triple thumb-linux-gnueabi -target-cpu cortex-m33 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-ARMV8M-MAIN-LINUX 
 // CHECK-ARMV8M-MAIN-LINUX: "target-features"="+armv8-m.main,+dsp,+fp-armv8d16sp,+fp16,+hwdiv,+thumb-mode,+vfp2sp,+vfp3d16sp,+vfp4d16sp"
 
+// RUN: %clang_cc1 -triple thumb-linux-gnueabi -target-cpu cortex-m55 -emit-llvm -o - %s | FileCheck %s --check-prefix=CHECK-ARMV81M-MAIN-LINUX
+// CHECK-ARMV81M-MAIN-LINUX: "target-features"="+armv8.1-m.main,+dsp,+fp-armv8d16,+fp-armv8d16sp,+fp16,+fp64,+fullfp16,+hwdiv,+lob,+mve,+mve.fp,+ras,+thumb-mode,+vfp2,+vfp2sp,+vfp3d16,+vfp3d16sp,+vfp4d16,+vfp4d16sp"
+
 void foo() {}
Index: clang/test/Driver/arm-cortex-cpus.c
===================================================================
--- clang/test/Driver/arm-cortex-cpus.c
+++ clang/test/Driver/arm-cortex-cpus.c
@@ -820,6 +820,9 @@
 // CHECK-CORTEX-M33:  "-cc1"{{.*}} "-triple" "thumbv8m.main-{{.*}} "-target-cpu" "cortex-m33"
 // CHECK-CORTEX-M35P:  "-cc1"{{.*}} "-triple" "thumbv8m.main-{{.*}} "-target-cpu" "cortex-m35p"
 
+// RUN: %clang -target arm -mcpu=cortex-m55 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CORTEX-M55 %s
+// CHECK-CORTEX-M55:  "-cc1"{{.*}} "-triple" "thumbv8.1m.main-{{.*}} "-target-cpu" "cortex-m55"
+
 // ================== Check whether -mcpu accepts mixed-case values.
 // RUN: %clang -target arm-linux-gnueabi -mcpu=Cortex-a5 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CASE-INSENSITIVE-CPUV7A %s
 // RUN: %clang -target arm-linux-gnueabi -mcpu=cortex-A7 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CASE-INSENSITIVE-CPUV7A %s
Index: clang/test/Preprocessor/arm-target-features.c
===================================================================
--- clang/test/Preprocessor/arm-target-features.c
+++ clang/test/Preprocessor/arm-target-features.c
@@ -674,6 +674,7 @@
 // RUN: %clang -target armv8m.main-none-linux-gnu -mcmse -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=V8M_CMSE %s
 // RUN: %clang -target arm-none-linux-gnu -mcpu=cortex-m33 -mcmse -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=V8M_CMSE %s
 // RUN: %clang -target arm -mcpu=cortex-m23 -mcmse -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=V8M_CMSE %s
+// RUN: %clang -target arm-none-linux-gnu -mcpu=cortex-m55 -mcmse -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=V8M_CMSE %s
 // V8M_CMSE-NOT: __ARM_FEATURE_CMSE 1
 // V8M_CMSE: #define __ARM_FEATURE_CMSE 3
 
@@ -726,6 +727,20 @@
 // M33-ALLOW-FP-INSTR: #define __ARM_FP 0x6
 // M33-ALLOW-FP-INSTR: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 1
 
+// Test whether predefines are as expected when targeting cortex-m55 (softfp FP ABI as default).
+// RUN: %clang -target arm-eabi -mcpu=cortex-m55 -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=M55 %s
+// M55: #define __ARM_ARCH 8
+// M55: #define __ARM_ARCH_8_1M_MAIN__ 1
+// M55: #define __ARM_ARCH_EXT_IDIV__ 1
+// M55-NOT: __ARM_ARCH_ISA_ARM
+// M55: #define __ARM_ARCH_ISA_THUMB 2
+// M55: #define __ARM_ARCH_PROFILE 'M'
+// M55-NOT: __ARM_FEATURE_CRC32
+// M55: #define __ARM_FEATURE_DSP 1
+// M55: #define __ARM_FEATURE_MVE 3
+// M55: #define __ARM_FP 0xe
+// M55: #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 1
+
 // Test whether predefines are as expected when targeting krait (soft FP as default).
 // RUN: %clang -target armv7 -mcpu=krait -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=KRAIT %s
 // RUN: %clang -target armv7 -mthumb -mcpu=krait -x c -E -dM %s -o - | FileCheck -match-full-lines --check-prefix=KRAIT %s
Index: llvm/include/llvm/Support/ARMTargetParser.def
===================================================================
--- llvm/include/llvm/Support/ARMTargetParser.def
+++ llvm/include/llvm/Support/ARMTargetParser.def
@@ -268,6 +268,8 @@
 ARM_CPU_NAME("cortex-m23", ARMV8MBaseline, FK_NONE, false, ARM::AEK_NONE)
 ARM_CPU_NAME("cortex-m33", ARMV8MMainline, FK_FPV5_SP_D16, false, ARM::AEK_DSP)
 ARM_CPU_NAME("cortex-m35p", ARMV8MMainline, FK_FPV5_SP_D16, false, ARM::AEK_DSP)
+ARM_CPU_NAME("cortex-m55", ARMV8_1MMainline, FK_FP_ARMV8_FULLFP16_D16, false,
+             (ARM::AEK_DSP | ARM::AEK_SIMD | ARM::AEK_FP | ARM::AEK_FP16))
 ARM_CPU_NAME("cortex-a32", ARMV8A, FK_CRYPTO_NEON_FP_ARMV8, false, ARM::AEK_CRC)
 ARM_CPU_NAME("cortex-a35", ARMV8A, FK_CRYPTO_NEON_FP_ARMV8, false, ARM::AEK_CRC)
 ARM_CPU_NAME("cortex-a53", ARMV8A, FK_CRYPTO_NEON_FP_ARMV8, false, ARM::AEK_CRC)
Index: llvm/lib/Support/Host.cpp
===================================================================
--- llvm/lib/Support/Host.cpp
+++ llvm/lib/Support/Host.cpp
@@ -192,6 +192,7 @@
             .Case("0xc20", "cortex-m0")
             .Case("0xc23", "cortex-m3")
             .Case("0xc24", "cortex-m4")
+            .Case("0xd22", "cortex-m55")
             .Case("0xd02", "cortex-a34")
             .Case("0xd04", "cortex-a35")
             .Case("0xd03", "cortex-a53")
Index: llvm/lib/Target/ARM/ARM.td
===================================================================
--- llvm/lib/Target/ARM/ARM.td
+++ llvm/lib/Target/ARM/ARM.td
@@ -1124,6 +1124,14 @@
                                                          FeatureUseMISched,
                                                          FeatureHasNoBranchPredictor]>;
 
+def : ProcessorModel<"cortex-m55", CortexM4Model,      [ARMv81mMainline,
+                                                         FeatureDSP,
+                                                         FeatureFPARMv8_D16,
+                                                         FeatureUseMISched,
+                                                         FeatureHasNoBranchPredictor,
+                                                         FeaturePrefLoopAlign32,
+                                                         FeatureHasSlowFPVMLx,
+                                                         HasMVEFloatOps]>;
 
 def : ProcNoItin<"cortex-a32",                           [ARMv8a,
                                                          FeatureHWDivThumb,
Index: llvm/test/CodeGen/ARM/build-attributes.ll
===================================================================
--- llvm/test/CodeGen/ARM/build-attributes.ll
+++ llvm/test/CodeGen/ARM/build-attributes.ll
@@ -233,6 +233,7 @@
 ; RUN: llc < %s -mtriple=thumbv8.1m.main-none-none-eabi | FileCheck %s --check-prefix=ARMv81M-MAIN
 ; RUN: llc < %s -mtriple=thumbv8.1m.main-none-none-eabi -mattr=+mve | FileCheck %s --check-prefix=ARMv81M-MAIN-MVEINT
 ; RUN: llc < %s -mtriple=thumbv8.1m.main-none-none-eabi -mattr=+mve.fp | FileCheck %s --check-prefix=ARMv81M-MAIN-MVEFP
+; RUN: llc < %s -mtriple=arm-none-none-eabi -mcpu=cortex-m55 | FileCheck %s --check-prefix=CORTEX-M55
 
 ; CPU-SUPPORTED-NOT: is not a recognized processor for this target
 
@@ -1722,6 +1723,28 @@
 ; ARMv81M-MAIN-MVEINT: .eabi_attribute 48, 1 @ Tag_MVE_arch
 ; ARMv81M-MAIN-MVEFP: .eabi_attribute 6, 21 @ Tag_CPU_arch
 ; ARMv81M-MAIN-MVEFP: .eabi_attribute 48, 2 @ Tag_MVE_arch
+
+; CORTEX-M55: .cpu cortex-m55
+; CORTEX-M55: .eabi_attribute 6, 21
+; CORTEX-M55: .eabi_attribute 7, 77
+; CORTEX-M55: .eabi_attribute 8, 0
+; CORTEX-M55: .eabi_attribute 9, 3
+; CORTEX-M55: .fpu fpv5-d16
+; CORTEX-M55: .eabi_attribute 36, 1
+; CORTEX-M55-NOT: .eabi_attribute 44
+; CORTEX-M55: .eabi_attribute 46, 1
+; CORTEX-M55: .eabi_attribute 34, 1
+; CORTEX-M55: .eabi_attribute 17, 1
+; CORTEX-M55-NOT: .eabi_attribute 19
+; CORTEX-M55: .eabi_attribute 20, 1
+; CORTEX-M55: .eabi_attribute 21, 1
+; CORTEX-M55: .eabi_attribute 23, 3
+; CORTEX-M55: .eabi_attribute 24, 1
+; CORTEX-M55: .eabi_attribute 25, 1
+; CORTEX-M55-NOT: .eabi_attribute 28
+; CORTEX-M55: .eabi_attribute 38, 1
+; CORTEX-M55: .eabi_attribute 14, 0
+
 define i32 @f(i64 %z) {
     ret i32 0
 }
Index: llvm/unittests/Support/TargetParserTest.cpp
===================================================================
--- llvm/unittests/Support/TargetParserTest.cpp
+++ llvm/unittests/Support/TargetParserTest.cpp
@@ -290,6 +290,11 @@
                          ARM::AEK_HWDIVTHUMB | ARM::AEK_DSP, "8-M.Mainline"));
   EXPECT_TRUE(testARMCPU("cortex-m35p", "armv8-m.main", "fpv5-sp-d16",
                          ARM::AEK_HWDIVTHUMB | ARM::AEK_DSP, "8-M.Mainline"));
+  EXPECT_TRUE(testARMCPU("cortex-m55", "armv8.1-m.main", "fp-armv8-fullfp16-d16",
+                         ARM::AEK_HWDIVTHUMB | ARM::AEK_DSP | ARM::AEK_SIMD |
+                         ARM::AEK_FP         | ARM::AEK_RAS | ARM::AEK_LOB |
+                         ARM::AEK_FP16,
+                        "8.1-M.Mainline"));
   EXPECT_TRUE(testARMCPU("iwmmxt", "iwmmxt", "none",
                          ARM::AEK_NONE, "iwmmxt"));
   EXPECT_TRUE(testARMCPU("xscale", "xscale", "none",
@@ -299,7 +304,7 @@
                          "7-S"));
 }
 
-static constexpr unsigned NumARMCPUArchs = 85;
+static constexpr unsigned NumARMCPUArchs = 86;
 
 TEST(TargetParserTest, testARMCPUArchList) {
   SmallVector<StringRef, NumARMCPUArchs> List;