Index: lib/CodeGen/CGOpenMPRuntime.cpp
===================================================================
--- lib/CodeGen/CGOpenMPRuntime.cpp
+++ lib/CodeGen/CGOpenMPRuntime.cpp
@@ -9648,6 +9648,307 @@
   }
 }
 
+// This are the Functions that are needed to mangle the name of the
+// vector functions generated by the compiler, according to the rules
+// defined in the "Vector Function ABI specifications for AArch64",
+// available at
+// https://developer.arm.com/products/software-development-tools/hpc/arm-compiler-for-hpc/vector-function-abi.
+
+/// Maps To Vector (MTV), as defined in 3.1.1 of the AAVFABI.
+///
+/// TODO: Need to implement the behavior for reference marked with a
+/// var or no linear modifiers (1.b in the section). For this, we
+/// need to extend ParamKindTy to support the linear modifiers.
+static bool getAArch64MTV(QualType QT, ParamKindTy Kind) {
+  QT = QT.getCanonicalType();
+
+  if (QT->isVoidType())
+    return false;
+
+  if (Kind == ParamKindTy::Uniform)
+    return false;
+
+  if (Kind == ParamKindTy::Linear)
+    return false;
+
+  // TODO: Handle linear references with modifiers
+
+  if (Kind == ParamKindTy::LinearWithVarStride)
+    return false;
+
+  return true;
+}
+
+/// Pass By Value (PBV), as defined in 3.1.2 of the AAVFABI.
+static bool getAArch64PBV(QualType QT, ASTContext &C) {
+  QT = QT.getCanonicalType();
+  unsigned Size = C.getTypeSize(QT);
+
+  // Only scalars and complex within 16 bytes wide set PVB to true.
+  if (Size != 8 && Size != 16 && Size != 32 && Size != 64 && Size != 128)
+    return false;
+
+  if (QT->isFloatingType())
+    return true;
+
+  if (QT->isIntegerType())
+    return true;
+
+  if (QT->isPointerType())
+    return true;
+
+  // TODO: Add support for complex types (section 3.1.2, item 2).
+
+  return false;
+}
+
+/// Computes the lane size (LS) of a return type or of an input parameter,
+/// as defined by `LS(P)` in 3.2.1 of the AAVFABI.
+/// TODO: Add support for references, section 3.2.1, item 1.
+static unsigned getAArch64LS(QualType QT, ParamKindTy Kind, ASTContext &C) {
+  if (getAArch64MTV(QT, Kind) && QT.getCanonicalType()->isPointerType()) {
+    QualType PTy = QT.getCanonicalType()->getPointeeType();
+    if (getAArch64PBV(PTy, C))
+      return C.getTypeSize(PTy);
+  }
+  if (getAArch64PBV(QT, C))
+    return C.getTypeSize(QT);
+
+  return C.getTypeSize(C.getUIntPtrType());
+}
+
+// Get Narrowest Data Size (NDS) and Widest Data Size (WDS) from the
+// signature of the scalar function, as defined in 3.2.2 of the
+// AAVFABI.
+static std::tuple<unsigned, unsigned, bool>
+getNDSWDS(const FunctionDecl *FD, ArrayRef<ParamAttrTy> ParamAttrs) {
+  QualType RetType = FD->getReturnType().getCanonicalType();
+
+  ASTContext &C = FD->getASTContext();
+
+  bool OutputBecomesInput = false;
+
+  llvm::SmallVector<unsigned, 8> Sizes;
+  if (!RetType->isVoidType()) {
+    Sizes.push_back(getAArch64LS(RetType, ParamKindTy::Vector, C));
+    if (!getAArch64PBV(RetType, C) && getAArch64MTV(RetType, {}))
+      OutputBecomesInput = true;
+  }
+  for (unsigned I = 0, E = FD->getNumParams(); I < E; ++I) {
+    QualType QT = FD->getParamDecl(I)->getType().getCanonicalType();
+    Sizes.push_back(getAArch64LS(QT, ParamAttrs[I].Kind, C));
+  }
+
+  assert(!Sizes.empty() && "Unable to determine NDS and WDS.");
+  // The LS of a function parameter / return value can only be a power
+  // of 2, starting from 8 bits, up to 128.
+  assert(std::all_of(Sizes.begin(), Sizes.end(),
+                     [](unsigned Size) {
+                       return Size == 8 || Size == 16 || Size == 32 ||
+                              Size == 64 || Size == 128;
+                     }) &&
+         "Invalid size");
+
+  return std::make_tuple(*std::min_element(std::begin(Sizes), std::end(Sizes)),
+                         *std::max_element(std::begin(Sizes), std::end(Sizes)),
+                         OutputBecomesInput);
+}
+
+/// Mangle the parameter part of the vector function name according to
+/// their OpenMP classification. The mangling function is defined in
+/// section 3.5 of the AAVFABI.
+static std::string mangleVectorParameters(ArrayRef<ParamAttrTy> ParamAttrs) {
+  SmallString<256> Buffer;
+  llvm::raw_svector_ostream Out(Buffer);
+  for (const auto &ParamAttr : ParamAttrs) {
+    switch (ParamAttr.Kind) {
+    case LinearWithVarStride:
+      Out << "ls" << ParamAttr.StrideOrArg;
+      break;
+    case Linear:
+      Out << 'l';
+      // Don't print the step value if it is not present or if it is
+      // equal to 1.
+      if (!!ParamAttr.StrideOrArg && ParamAttr.StrideOrArg != 1)
+        Out << ParamAttr.StrideOrArg;
+      break;
+    case Uniform:
+      Out << 'u';
+      break;
+    case Vector:
+      Out << 'v';
+      break;
+    }
+
+    if (!!ParamAttr.Alignment)
+      Out << 'a' << ParamAttr.Alignment;
+  }
+
+  return Out.str();
+}
+
+// Function used to add the attribute. The parameter `VLEN` is
+// templated to allow the use of "x" when targeting scalable functions
+// for SVE.
+template <typename T>
+static void addAArch64VectorName(T VLEN, StringRef LMask, StringRef Prefix,
+                                 char ISA, StringRef ParSeq,
+                                 StringRef MangledName, bool OutputBecomesInput,
+                                 llvm::Function *Fn) {
+  SmallString<256> Buffer;
+  llvm::raw_svector_ostream Out(Buffer);
+  Out << Prefix << ISA << LMask << VLEN;
+  if (OutputBecomesInput)
+    Out << "v";
+  Out << ParSeq << "_" << MangledName;
+  Fn->addFnAttr(Out.str());
+}
+
+// Helper function to generate the Advanced SIMD names depending on
+// the value of the NDS when simdlen is not present.
+static void addAArch64AdvSIMDNDSNames(unsigned NDS, StringRef Mask,
+                                      StringRef Prefix, char ISA,
+                                      StringRef ParSeq, StringRef MangledName,
+                                      bool OutputBecomesInput,
+                                      llvm::Function *Fn) {
+  switch (NDS) {
+  case 8:
+    addAArch64VectorName(8, Mask, Prefix, ISA, ParSeq, MangledName,
+                         OutputBecomesInput, Fn);
+    addAArch64VectorName(16, Mask, Prefix, ISA, ParSeq, MangledName,
+                         OutputBecomesInput, Fn);
+    break;
+  case 16:
+    addAArch64VectorName(4, Mask, Prefix, ISA, ParSeq, MangledName,
+                         OutputBecomesInput, Fn);
+    addAArch64VectorName(8, Mask, Prefix, ISA, ParSeq, MangledName,
+                         OutputBecomesInput, Fn);
+    break;
+  case 32:
+    addAArch64VectorName(2, Mask, Prefix, ISA, ParSeq, MangledName,
+                         OutputBecomesInput, Fn);
+    addAArch64VectorName(4, Mask, Prefix, ISA, ParSeq, MangledName,
+                         OutputBecomesInput, Fn);
+    break;
+  case 64:
+  case 128:
+    addAArch64VectorName(2, Mask, Prefix, ISA, ParSeq, MangledName,
+                         OutputBecomesInput, Fn);
+    break;
+  default:
+    llvm_unreachable("Scalar type is too wide.");
+  }
+}
+
+/// Emit vector function attributes for AArch64, as defined in the AAVFABI.
+static void emitAArch64DeclareSimdFunction(
+    CodeGenModule &CGM, const FunctionDecl *FD, unsigned UserVLEN,
+    ArrayRef<ParamAttrTy> ParamAttrs,
+    OMPDeclareSimdDeclAttr::BranchStateTy State, StringRef MangledName,
+    char ISA, unsigned VecRegSize, llvm::Function *Fn, SourceLocation SLoc) {
+
+  // Get basic data for building the vector signature.
+  const auto Data = getNDSWDS(FD, ParamAttrs);
+  const unsigned NDS = std::get<0>(Data);
+  const unsigned WDS = std::get<1>(Data);
+  const bool OutputBecomesInput = std::get<2>(Data);
+
+  // Check the values provided via `simdlen` by the user.
+  // 1. A `simdlen(1)` doesn't produce vector signatures,
+  if (UserVLEN == 1) {
+    unsigned DiagID = CGM.getDiags().getCustomDiagID(
+        DiagnosticsEngine::Warning,
+        "The clause simdlen(1) has no effect when targeting aarch64.");
+    CGM.getDiags().Report(SLoc, DiagID);
+    return;
+  }
+
+  // 2. Section 3.3.1, item 1: user input must be a power of 2 for
+  // Advanced SIMD output.
+  if (ISA == 'n' && UserVLEN && !llvm::isPowerOf2_32(UserVLEN)) {
+    unsigned DiagID = CGM.getDiags().getCustomDiagID(
+        DiagnosticsEngine::Warning, "The value specified in simdlen must be a "
+                                    "power of 2 when targeting Advanced SIMD.");
+    CGM.getDiags().Report(SLoc, DiagID);
+    return;
+  }
+
+  // 3. Section 3.4.1. SVE fixed lengh must obey the architectural
+  // limits.
+  if (ISA == 's' && UserVLEN != 0) {
+    if ((UserVLEN * WDS > 2048) || (UserVLEN * WDS % 128 != 0)) {
+      unsigned DiagID = CGM.getDiags().getCustomDiagID(
+          DiagnosticsEngine::Warning, "The clause simdlen must fit the %0-bit "
+                                      "lanes in the architectural constraints "
+                                      "for SVE (min is 128-bit, max is "
+                                      "2048-bit, by steps of 128-bit)");
+      CGM.getDiags().Report(SLoc, DiagID) << WDS;
+      return;
+    }
+  }
+
+  // Sort out parameter sequence.
+  const std::string ParSeq = mangleVectorParameters(ParamAttrs);
+  StringRef Prefix = "_ZGV";
+  // Generate simdlen from user input (if any).
+  if (UserVLEN) {
+    if (ISA == 's') {
+      // SVE generates only a masked function.
+      addAArch64VectorName(UserVLEN, "M", Prefix, ISA, ParSeq, MangledName,
+                           OutputBecomesInput, Fn);
+    } else {
+      assert(ISA == 'n' && "Expected ISA either 's' or 'n'.");
+      // Advanced SIMD generates one or two functions, depending on
+      // the `[not]inbranch` clause.
+      switch (State) {
+      case OMPDeclareSimdDeclAttr::BS_Undefined:
+        addAArch64VectorName(UserVLEN, "N", Prefix, ISA, ParSeq, MangledName,
+                             OutputBecomesInput, Fn);
+        addAArch64VectorName(UserVLEN, "M", Prefix, ISA, ParSeq, MangledName,
+                             OutputBecomesInput, Fn);
+        break;
+      case OMPDeclareSimdDeclAttr::BS_Notinbranch:
+        addAArch64VectorName(UserVLEN, "N", Prefix, ISA, ParSeq, MangledName,
+                             OutputBecomesInput, Fn);
+        break;
+      case OMPDeclareSimdDeclAttr::BS_Inbranch:
+        addAArch64VectorName(UserVLEN, "M", Prefix, ISA, ParSeq, MangledName,
+                             OutputBecomesInput, Fn);
+        break;
+      }
+    }
+  } else {
+    // If no user simdlen is provided, follow the AAVFABI rules for
+    // generating the vector length.
+    if (ISA == 's') {
+      // SVE, section 3.4.1, item 1.
+      addAArch64VectorName("x", "M", Prefix, ISA, ParSeq, MangledName,
+                           OutputBecomesInput, Fn);
+    } else {
+      assert(ISA == 'n' && "Expected ISA either 's' or 'n'.");
+      // Advanced SIMD, Section 3.3.1 of the AAVFABI, generates one or
+      // two vector names depending on the use of the clause
+      // `[not]inbranch`.
+      switch (State) {
+      case OMPDeclareSimdDeclAttr::BS_Undefined:
+        addAArch64AdvSIMDNDSNames(NDS, "N", Prefix, ISA, ParSeq, MangledName,
+                                  OutputBecomesInput, Fn);
+        addAArch64AdvSIMDNDSNames(NDS, "M", Prefix, ISA, ParSeq, MangledName,
+                                  OutputBecomesInput, Fn);
+        break;
+      case OMPDeclareSimdDeclAttr::BS_Notinbranch:
+        addAArch64AdvSIMDNDSNames(NDS, "N", Prefix, ISA, ParSeq, MangledName,
+                                  OutputBecomesInput, Fn);
+        break;
+      case OMPDeclareSimdDeclAttr::BS_Inbranch:
+        addAArch64AdvSIMDNDSNames(NDS, "M", Prefix, ISA, ParSeq, MangledName,
+                                  OutputBecomesInput, Fn);
+        break;
+      }
+    }
+  }
+}
+
 void CGOpenMPRuntime::emitDeclareSimdFunction(const FunctionDecl *FD,
                                               llvm::Function *Fn) {
   ASTContext &C = CGM.getContext();
@@ -9734,12 +10035,26 @@
         ++MI;
       }
       llvm::APSInt VLENVal;
-      if (const Expr *VLEN = Attr->getSimdlen())
-        VLENVal = VLEN->EvaluateKnownConstInt(C);
+      SourceLocation ExprLoc;
+      const Expr *VLENExpr = Attr->getSimdlen();
+      if (VLENExpr) {
+        VLENVal = VLENExpr->EvaluateKnownConstInt(C);
+        ExprLoc = VLENExpr->getExprLoc();
+      }
       OMPDeclareSimdDeclAttr::BranchStateTy State = Attr->getBranchState();
       if (CGM.getTriple().getArch() == llvm::Triple::x86 ||
-          CGM.getTriple().getArch() == llvm::Triple::x86_64)
+          CGM.getTriple().getArch() == llvm::Triple::x86_64) {
         emitX86DeclareSimdFunction(FD, Fn, VLENVal, ParamAttrs, State);
+      } else if (CGM.getTriple().getArch() == llvm::Triple::aarch64) {
+        unsigned VLEN = VLENVal.getExtValue();
+        StringRef MangledName = Fn->getName();
+        if (CGM.getTarget().hasFeature("sve"))
+          emitAArch64DeclareSimdFunction(CGM, FD, VLEN, ParamAttrs, State,
+                                         MangledName, 's', 128, Fn, ExprLoc);
+        if (CGM.getTarget().hasFeature("neon"))
+          emitAArch64DeclareSimdFunction(CGM, FD, VLEN, ParamAttrs, State,
+                                         MangledName, 'n', 128, Fn, ExprLoc);
+      }
     }
     FD = FD->getPreviousDecl();
   }
Index: test/OpenMP/Inputs/declare-simd-fix.h
===================================================================
--- test/OpenMP/Inputs/declare-simd-fix.h
+++ test/OpenMP/Inputs/declare-simd-fix.h
@@ -0,0 +1,8 @@
+#ifndef LLVM_CLANG_TEST_OPENMP_INPUTS_DECLARE_SIMD_FIX_H
+#define LLVM_CLANG_TEST_OPENMP_INPUTS_DECLARE_SIMD_FIX_H
+
+#pragma omp declare simd
+float foo(float a, float b, int c);
+float bar(float a, float b, int c);
+
+#endif
Index: test/OpenMP/declare_simd_aarch64.c
===================================================================
--- test/OpenMP/declare_simd_aarch64.c
+++ test/OpenMP/declare_simd_aarch64.c
@@ -0,0 +1,190 @@
+// -fopemp and -fopenmp-simd behavior are expected to be the same.
+
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +neon -fopenmp -x c -emit-llvm %s -o - -femit-all-decls | FileCheck %s --check-prefix=AARCH64
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +neon -fopenmp-simd -x c -emit-llvm %s -o - -femit-all-decls | FileCheck %s --check-prefix=AARCH64
+
+#pragma omp declare simd
+#pragma omp declare simd simdlen(2)
+#pragma omp declare simd simdlen(6)
+#pragma omp declare simd simdlen(8)
+double foo(float x);
+
+// AARCH64: "_ZGVnM2v_foo" "_ZGVnM4v_foo" "_ZGVnM8v_foo" "_ZGVnN2v_foo" "_ZGVnN4v_foo" "_ZGVnN8v_foo"
+// AARCH64-NOT: _ZGVnN6v_foo
+
+void foo_loop(double *x, float *y, int N) {
+  for (int i = 0; i < N; ++i) {
+    x[i] = foo(y[i]);
+  }
+}
+
+// make sure that the following two function by default gets generated
+// with 4 and 2 lanes, as descrived in the vector ABI
+#pragma omp declare simd notinbranch
+float bar(double x);
+#pragma omp declare simd notinbranch
+double baz(float x);
+
+// AARCH64: "_ZGVnN2v_baz" "_ZGVnN4v_baz"
+// AARCH64-NOT: baz
+// AARCH64: "_ZGVnN2v_bar" "_ZGVnN4v_bar"
+// AARCH64-NOT: bar
+
+void baz_bar_loop(double *x, float *y, int N) {
+  for (int i = 0; i < N; ++i) {
+    x[i] = baz(y[i]);
+    y[i] = bar(x[i]);
+  }
+}
+
+  /***************************/
+  /*  32-bit integer tests   */
+  /***************************/
+
+#pragma omp declare simd
+#pragma omp declare simd simdlen(2)
+#pragma omp declare simd simdlen(6)
+#pragma omp declare simd simdlen(8)
+long foo_int(int x);
+
+// AARCH64: "_ZGVnN2v_foo_int" "_ZGVnN4v_foo_int" "_ZGVnN8v_foo_int"
+// No non power of two
+// AARCH64-NOT: _ZGVnN6v_foo_int
+
+void foo_int_loop(long *x, int *y, int N) {
+  for (int i = 0; i < N; ++i) {
+    x[i] = foo_int(y[i]);
+  }
+}
+
+#pragma omp declare simd
+char simple_8bit(char);
+// AARCH64: "_ZGVnM16v_simple_8bit" "_ZGVnM8v_simple_8bit" "_ZGVnN16v_simple_8bit" "_ZGVnN8v_simple_8bit"
+#pragma omp declare simd
+short simple_16bit(short);
+// AARCH64: "_ZGVnM4v_simple_16bit" "_ZGVnM8v_simple_16bit" "_ZGVnN4v_simple_16bit" "_ZGVnN8v_simple_16bit"
+#pragma omp declare simd
+int simple_32bit(int);
+// AARCH64: "_ZGVnM2v_simple_32bit" "_ZGVnM4v_simple_32bit" "_ZGVnN2v_simple_32bit" "_ZGVnN4v_simple_32bit"
+#pragma omp declare simd
+long simple_64bit(long);
+// AARCH64: "_ZGVnM2v_simple_64bit" "_ZGVnN2v_simple_64bit"
+
+#pragma omp declare simd
+#pragma omp declare simd simdlen(32)
+char a01(int x);
+// AARCH64: "_ZGVnN16v_a01" "_ZGVnN32v_a01" "_ZGVnN8v_a01"
+// AARCH64-NOT: a01
+
+#pragma omp declare simd
+#pragma omp declare simd simdlen(2)
+long a02(short x);
+// AARCH64:  "_ZGVnN2v_a02" "_ZGVnN4v_a02" "_ZGVnN8v_a02"
+
+// AARCH64-NOT: a02
+/************/
+/* pointers */
+/************/
+
+#pragma omp declare simd
+int b01(int *x);
+// AARCH64: "_ZGVnN4v_b01"
+// AARCH64-NOT: b01
+
+#pragma omp declare simd
+char b02(char *);
+// AARCH64: "_ZGVnN16v_b02" "_ZGVnN8v_b02"
+// AARCH64-NOT: b02
+
+#pragma omp declare simd
+double *b03(double *);
+// AARCH64: "_ZGVnN2v_b03"
+// AARCH64-NOT: b03
+
+/***********/
+/* masking */
+/***********/
+
+#pragma omp declare simd inbranch
+int c01(double *x, short y);
+// AARCH64: "_ZGVnM8vv_c01"
+// AARCH64-NOT: c01
+
+#pragma omp declare simd inbranch uniform(x)
+double c02(double *x, char y);
+// AARCH64: "_ZGVnM16uv_c02" "_ZGVnM8uv_c02"
+// AARCH64-NOT: c02
+
+/*************************/
+/* sincos-like signature */
+/*************************/
+#pragma omp declare simd linear(sin) linear(cos)
+void sincos(double in, double *sin, double *cos);
+// AARCH64: "_ZGVnN2vll_sincos"
+// AARCH64-NOT: sincos
+
+#pragma omp declare simd linear(sin : 1) linear(cos : 2)
+void SinCos(double in, double *sin, double *cos);
+// AARCH64: "_ZGVnN2vll2_SinCos"
+// AARCH64-NOT: SinCos
+
+// Selection of tests based on the examples provided in chapter 5 of
+// the Vector Function ABI specifications for AArch64, at
+// https://developer.arm.com/products/software-development-tools/hpc/arm-compiler-for-hpc/vector-function-abi.
+
+// Listing 2, p. 18
+#pragma omp declare simd inbranch uniform(x) linear(val(i) : 4)
+int foo2(int *x, int i);
+// AARCH64: "_ZGVnM2ul4_foo2" "_ZGVnM4ul4_foo2"
+// AARCH64-NOT: foo2
+
+// Listing 3, p. 18
+#pragma omp declare simd inbranch uniform(x, c) linear(i \
+                                                       : c)
+int foo3(int *x, int i, unsigned char c);
+// AARCH64: "_ZGVnM16uls2u_foo3" "_ZGVnM8uls2u_foo3"
+// AARCH64-NOT: foo3
+
+// Listing 6, p. 19
+#pragma omp declare simd linear(x) aligned(x : 16) simdlen(4)
+int foo4(int *x, float y);
+// AARCH64: "_ZGVnM4la16v_foo4" "_ZGVnN4la16v_foo4"
+// AARCH64-NOT: foo4
+
+static int *I;
+static char *C;
+static short *S;
+static long *L;
+static float *F;
+static double *D;
+void do_something() {
+  simple_8bit(*C);
+  simple_16bit(*S);
+  simple_32bit(*I);
+  simple_64bit(*L);
+  *C = a01(*I);
+  *L = a02(*S);
+  *I = b01(I);
+  *C = b02(C);
+  D = b03(D);
+  *I = c01(D, *S);
+  *D = c02(D, *S);
+  sincos(*D, D, D);
+  SinCos(*D, D, D);
+  foo2(I, *I);
+  foo3(I, *I, *C);
+  foo4(I, *F);
+}
+
+typedef struct S {
+  char R, G, B;
+} STy;
+#pragma omp declare simd notinbranch
+STy DoRGB(STy x);
+// AARCH64: "_ZGVnN2v_DoRGB"
+
+static STy *RGBData;
+
+void do_rgb_stuff() {
+  DoRGB(*RGBData);
+}
Index: test/OpenMP/declare_simd_aarch64.cpp
===================================================================
--- test/OpenMP/declare_simd_aarch64.cpp
+++ test/OpenMP/declare_simd_aarch64.cpp
@@ -0,0 +1,37 @@
+// -fopemp and -fopenmp-simd behavior are expected to be the same.
+
+// RUN: %clang_cc1 -verify -triple aarch64-linux-gnu -target-feature +neon -fopenmp -x c++ -emit-llvm %s -o - -femit-all-decls -verify| FileCheck %s --check-prefix=ADVSIMD
+// RUN: %clang_cc1 -verify -triple aarch64-linux-gnu -target-feature +sve -fopenmp -x c++ -emit-llvm %s -o - -femit-all-decls -verify| FileCheck %s --check-prefix=SVE
+
+// RUN: %clang_cc1 -verify -triple aarch64-linux-gnu -target-feature +neon -fopenmp-simd -x c++ -emit-llvm %s -o - -femit-all-decls -verify| FileCheck %s --check-prefix=ADVSIMD
+// RUN: %clang_cc1 -verify -triple aarch64-linux-gnu -target-feature +sve -fopenmp-simd -x c++ -emit-llvm %s -o - -femit-all-decls -verify| FileCheck %s --check-prefix=SVE
+
+// expected-no-diagnostics
+
+#pragma omp declare simd
+double f(double x);
+
+#pragma omp declare simd
+float f(float x);
+
+void aaa(double *x, double *y, int N) {
+  for (int i = 0; i < N; ++i) {
+    x[i] = f(y[i]);
+  }
+}
+
+void aaa(float *x, float *y, int N) {
+  for (int i = 0; i < N; ++i) {
+    x[i] = f(y[i]);
+  }
+}
+
+// ADVSIMD: "_ZGVnN2v__Z1fd"
+// ADVSIMD-NOT: _Z1fd
+// ADVSIMD: "_ZGVnN4v__Z1ff"
+// ADVSIMD-NOT: _Z1fF
+
+// SVE: "_ZGVsMxv__Z1fd"
+// SVE-NOT: _Z1fd
+// SVE: "_ZGVsMxv__Z1ff"
+// SVE-NOT: _Z1ff
Index: test/OpenMP/declare_simd_aarch64_complex.c
===================================================================
--- test/OpenMP/declare_simd_aarch64_complex.c
+++ test/OpenMP/declare_simd_aarch64_complex.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +neon -fopenmp -x c -std=c11 -emit-llvm %s -o - -femit-all-decls | FileCheck %s
+
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +sve -fopenmp -x c -std=c11 -emit-llvm %s -o - -femit-all-decls | FileCheck %s --check-prefix=SVE
+
+#pragma omp declare simd
+#pragma omp declare simd simdlen(4) notinbranch
+double _Complex double_complex(double _Complex);
+// CHECK:  "_ZGVnM2v_double_complex" "_ZGVnN2v_double_complex" "_ZGVnN4v_double_complex"
+// CHECK-NOT: double_complex
+// SVE:   "_ZGVsM4v_double_complex" "_ZGVsMxv_double_complex"
+// SVE-NOT: double_complex
+
+#pragma omp declare simd
+#pragma omp declare simd simdlen(8) notinbranch
+float _Complex float_complex(float _Complex);
+// CHECK:  "_ZGVnM2v_float_complex" "_ZGVnN2v_float_complex" "_ZGVnN8v_float_complex"
+// CHECK-NOT: float_complex
+// SVE: "_ZGVsM8v_float_complex" "_ZGVsMxv_float_complex"
+// SVE-NOT: float_complex
+
+static double _Complex *DC;
+static float _Complex *DF;
+void call_the_complex_functions() {
+  double_complex(*DC);
+  float_complex(*DF);
+}
Index: test/OpenMP/declare_simd_aarch64_fix.c
===================================================================
--- test/OpenMP/declare_simd_aarch64_fix.c
+++ test/OpenMP/declare_simd_aarch64_fix.c
@@ -0,0 +1,37 @@
+// This test is making sure that no crash happens.
+
+// RUN: %clang -o - -fno-fast-math -S -target aarch64-linux-gnu \
+// RUN: -fopenmp -O3 -march=armv8-a  -c %s | FileCheck %s
+
+// RUN: %clang -o - -fno-fast-math -S -target aarch64-linux-gnu \
+// RUN: -fopenmp-simd -O3 -march=armv8-a  -c %s | FileCheck %s
+
+// RUN: %clang -o - -fno-fast-math -S -target aarch64-linux-gnu \
+// RUN: -fopenmp -O3 -march=armv8-a+sve  -c %s | FileCheck %s
+
+// RUN: %clang -o - -fno-fast-math -S -target aarch64-linux-gnu \
+// RUN: -fopenmp-simd -O3 -march=armv8-a+sve  -c %s | FileCheck %s
+
+// loop in the user code, in user_code.c
+#include "Inputs/declare-simd-fix.h"
+
+// CHECK-LABEL: do_something:
+void do_something(int *a, double *b, unsigned N) {
+  for (unsigned i = 0; i < N; ++i) {
+    a[i] = foo(b[0], b[0], 1);
+  }
+}
+
+// CHECK-LABEL: do_something_else:
+void do_something_else(int *a, double *b, unsigned N) {
+  for (unsigned i = 0; i < N; ++i) {
+    a[i] = foo(1.1, 1.2, 1);
+  }
+}
+
+// CHECK-LABEL: do_something_more:
+void do_something_more(int *a, double *b, unsigned N) {
+  for (unsigned i = 0; i < N; ++i) {
+    a[i] = foo(b[i], b[i], a[1]);
+  }
+}
Index: test/OpenMP/declare_simd_aarch64_sve.c
===================================================================
--- test/OpenMP/declare_simd_aarch64_sve.c
+++ test/OpenMP/declare_simd_aarch64_sve.c
@@ -0,0 +1,43 @@
+// -fopemp and -fopenmp-simd behavior are expected to be the same
+
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +sve \
+// RUN:  -fopenmp -x c -emit-llvm %s -o - -femit-all-decls | FileCheck %s
+
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +sve \
+// RUN:  -fopenmp-simd -x c -emit-llvm %s -o - -femit-all-decls | FileCheck %s
+
+#pragma omp declare simd
+#pragma omp declare simd notinbranch
+#pragma omp declare simd simdlen(2)
+#pragma omp declare simd simdlen(4)
+#pragma omp declare simd simdlen(5) // not a multiple of 128-bits
+#pragma omp declare simd simdlen(6)
+#pragma omp declare simd simdlen(8)
+#pragma omp declare simd simdlen(32)
+#pragma omp declare simd simdlen(34) // requires more than 2048 bits
+double foo(float x);
+
+// CHECK-DAG: "_ZGVsM2v_foo" "_ZGVsM32v_foo" "_ZGVsM4v_foo" "_ZGVsM6v_foo" "_ZGVsM8v_foo" "_ZGVsMxv_foo"
+// CHECK-NOT: _ZGVsN
+// CHECK-NOT: _ZGVsM5v_foo
+// CHECK-NOT: _ZGVsM34v_foo
+// CHECK-NOT: foo
+
+void foo_loop(double *x, float *y, int N) {
+  for (int i = 0; i < N; ++i) {
+    x[i] = foo(y[i]);
+  }
+}
+
+  // test integers
+
+#pragma omp declare simd notinbranch
+char a01(int x);
+// CHECK-DAG: _ZGVsMxv_a01
+// CHECK-NOT: a01
+
+static int *in;
+static char *out;
+void do_something() {
+  *out = a01(*in);
+}
Index: test/OpenMP/declare_simd_aarch64_warning_advsimd.c
===================================================================
--- test/OpenMP/declare_simd_aarch64_warning_advsimd.c
+++ test/OpenMP/declare_simd_aarch64_warning_advsimd.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +neon  -fopenmp  %s -S  -o %t -verify
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +neon  -fopenmp-simd  %s -S  -o %t -verify
+
+#pragma omp declare simd simdlen(6)
+double foo(float x);
+// expected-warning@-2{{The value specified in simdlen must be a power of 2 when targeting Advanced SIMD.}}
+#pragma omp declare simd simdlen(1)
+float bar(double x);
+// expected-warning@-2{{The clause simdlen(1) has no effect when targeting aarch64.}}
+
+void foo_loop(double *x, float *y, int N) {
+  for (int i = 0; i < N; ++i) {
+    x[i] = foo(y[i]);
+    y[i] = bar(x[i]);
+  }
+}
Index: test/OpenMP/declare_simd_aarch64_warning_sve.c
===================================================================
--- test/OpenMP/declare_simd_aarch64_warning_sve.c
+++ test/OpenMP/declare_simd_aarch64_warning_sve.c
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +sve  -fopenmp  %s -S  -o %t -verify
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -target-feature +sve  -fopenmp-simd  %s -S  -o %t -verify
+
+#pragma omp declare simd simdlen(66)
+double foo(float x);
+//expected-warning@-2{{The clause simdlen must fit the 64-bit lanes in the architectural constraints for SVE (min is 128-bit, max is 2048-bit, by steps of 128-bit)}}
+
+void foo_loop(double *x, float *y, int N) {
+  for (int i = 0; i < N; ++i) {
+    x[i] = foo(y[i]);
+  }
+}