diff --git a/clang/test/CodeGen/SystemZ/systemz-inline-asm.c b/clang/test/CodeGen/SystemZ/systemz-inline-asm.c
--- a/clang/test/CodeGen/SystemZ/systemz-inline-asm.c
+++ b/clang/test/CodeGen/SystemZ/systemz-inline-asm.c
@@ -123,7 +123,7 @@
 long double test_f128(long double f, long double g) {
   asm("axbr %0, %2" : "=f" (f) : "0" (f), "f" (g));
   return f;
-// CHECK: define{{.*}} void @test_f128(fp128* noalias nocapture sret(fp128) align 8 [[DEST:%.*]], fp128* nocapture readonly %0, fp128* nocapture readonly %1)
+// CHECK: define{{.*}} void @test_f128(fp128* noalias nocapture writeonly sret(fp128) align 8 [[DEST:%.*]], fp128* nocapture readonly %0, fp128* nocapture readonly %1)
 // CHECK: %f = load fp128, fp128* %0
 // CHECK: %g = load fp128, fp128* %1
 // CHECK: [[RESULT:%.*]] = tail call fp128 asm "axbr $0, $2", "=f,0,f"(fp128 %f, fp128 %g)
diff --git a/clang/test/CodeGen/aarch64-sve-acle-__ARM_FEATURE_SVE_VECTOR_OPERATORS.c b/clang/test/CodeGen/aarch64-sve-acle-__ARM_FEATURE_SVE_VECTOR_OPERATORS.c
--- a/clang/test/CodeGen/aarch64-sve-acle-__ARM_FEATURE_SVE_VECTOR_OPERATORS.c
+++ b/clang/test/CodeGen/aarch64-sve-acle-__ARM_FEATURE_SVE_VECTOR_OPERATORS.c
@@ -59,7 +59,7 @@
 // CHECK128-NEXT:    ret <16 x i8> [[CASTFIXEDSVE]]
 
 // CHECK-LABEL: define{{.*}} void @f2(
-// CHECK-SAME:   <[[#div(VBITS,8)]] x i8>* noalias nocapture sret(<[[#div(VBITS,8)]] x i8>) align 16 %agg.result, <[[#div(VBITS,8)]] x i8>* nocapture readonly %0)
+// CHECK-SAME:   <[[#div(VBITS,8)]] x i8>* noalias nocapture writeonly sret(<[[#div(VBITS,8)]] x i8>) align 16 %agg.result, <[[#div(VBITS,8)]] x i8>* nocapture readonly %0)
 // CHECK-NEXT: entry:
 // CHECK-NEXT:   [[X:%.*]] = load <[[#div(VBITS,8)]] x i8>, <[[#div(VBITS,8)]] x i8>* [[TMP0:%.*]], align 16, [[TBAA6:!tbaa !.*]]
 // CHECK-NEXT:   [[TMP1:%.*]] = call <vscale x 16 x i1> @llvm.aarch64.sve.ptrue.nxv16i1(i32 31)
diff --git a/clang/test/CodeGen/arm-vfp16-arguments2.cpp b/clang/test/CodeGen/arm-vfp16-arguments2.cpp
--- a/clang/test/CodeGen/arm-vfp16-arguments2.cpp
+++ b/clang/test/CodeGen/arm-vfp16-arguments2.cpp
@@ -37,27 +37,27 @@
   B1 M[1];
 };
 
-// CHECK-SOFT: define{{.*}} void @_Z2f12S1(%struct.S1* noalias nocapture sret(%struct.S1) align 8 %agg.result, [2 x i64] %s1.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f12S1(%struct.S1* noalias nocapture writeonly sret(%struct.S1) align 8 %agg.result, [2 x i64] %s1.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f12S1([2 x <2 x i32>] returned %s1.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S1 @_Z2f12S1(%struct.S1 returned %s1.coerce)
 struct S1 f1(struct S1 s1) { return s1; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f22S2(%struct.S2* noalias nocapture sret(%struct.S2) align 8 %agg.result, [4 x i32] %s2.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f22S2(%struct.S2* noalias nocapture writeonly sret(%struct.S2) align 8 %agg.result, [4 x i32] %s2.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f22S2([2 x <2 x i32>] returned %s2.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S2 @_Z2f22S2(%struct.S2 returned %s2.coerce)
 struct S2 f2(struct S2 s2) { return s2; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f32S3(%struct.S3* noalias nocapture sret(%struct.S3) align 8 %agg.result, [2 x i64] %s3.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f32S3(%struct.S3* noalias nocapture writeonly sret(%struct.S3) align 8 %agg.result, [2 x i64] %s3.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f32S3([2 x <2 x i32>] returned %s3.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S3 @_Z2f32S3(%struct.S3 returned %s3.coerce)
 struct S3 f3(struct S3 s3) { return s3; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f42S4(%struct.S4* noalias nocapture sret(%struct.S4) align 8 %agg.result, [2 x i64] %s4.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f42S4(%struct.S4* noalias nocapture writeonly sret(%struct.S4) align 8 %agg.result, [2 x i64] %s4.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f42S4([2 x <2 x i32>] returned %s4.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S4 @_Z2f42S4(%struct.S4 returned %s4.coerce)
 struct S4 f4(struct S4 s4) { return s4; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f52S5(%struct.S5* noalias nocapture sret(%struct.S5) align 8 %agg.result, [2 x i64] %s5.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f52S5(%struct.S5* noalias nocapture writeonly sret(%struct.S5) align 8 %agg.result, [2 x i64] %s5.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc %struct.S5 @_Z2f52S5(%struct.S5 returned %s5.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S5 @_Z2f52S5(%struct.S5 returned %s5.coerce)
 struct S5 f5(struct S5 s5) { return s5; }
diff --git a/clang/test/CodeGen/mips-vector-return.c b/clang/test/CodeGen/mips-vector-return.c
--- a/clang/test/CodeGen/mips-vector-return.c
+++ b/clang/test/CodeGen/mips-vector-return.c
@@ -8,14 +8,14 @@
 typedef double v4df __attribute__ ((__vector_size__ (32)));
 typedef int v4i32 __attribute__ ((__vector_size__ (16)));
 
-// O32-LABEL: define dso_local void @test_v4sf(<4 x float>* noalias nocapture sret
+// O32-LABEL: define dso_local void @test_v4sf(<4 x float>* noalias nocapture writeonly sret
 // N64: define inreg { i64, i64 } @test_v4sf
 v4sf test_v4sf(float a) {
   return (v4sf){0.0f, a, 0.0f, 0.0f};
 }
 
-// O32-LABEL: define dso_local void @test_v4df(<4 x double>* noalias nocapture sret
-// N64-LABEL: define void @test_v4df(<4 x double>* noalias nocapture sret
+// O32-LABEL: define dso_local void @test_v4df(<4 x double>* noalias nocapture writeonly sret
+// N64-LABEL: define void @test_v4df(<4 x double>* noalias nocapture writeonly sret
 v4df test_v4df(double a) {
   return (v4df){0.0, a, 0.0, 0.0};
 }
diff --git a/clang/test/CodeGen/mips64-nontrivial-return.cpp b/clang/test/CodeGen/mips64-nontrivial-return.cpp
--- a/clang/test/CodeGen/mips64-nontrivial-return.cpp
+++ b/clang/test/CodeGen/mips64-nontrivial-return.cpp
@@ -10,7 +10,7 @@
 
 extern D gd0;
 
-// CHECK: _Z4foo1v(%class.D* noalias nocapture sret
+// CHECK: _Z4foo1v(%class.D* noalias nocapture writeonly sret
 
 D foo1(void) {
   return gd0;
diff --git a/clang/test/CodeGen/ms-mixed-ptr-sizes.c b/clang/test/CodeGen/ms-mixed-ptr-sizes.c
--- a/clang/test/CodeGen/ms-mixed-ptr-sizes.c
+++ b/clang/test/CodeGen/ms-mixed-ptr-sizes.c
@@ -7,32 +7,32 @@
 };
 void use_foo(struct Foo *f);
 void test_sign_ext(struct Foo *f, int * __ptr32 __sptr i) {
-// X64-LABEL: define dso_local void @test_sign_ext({{.*}}i32 addrspace(270)* %i)
-// X86-LABEL: define dso_local void @test_sign_ext(%struct.Foo* %f, i32* %i)
+// X64-LABEL: define dso_local void @test_sign_ext({{.*}}i32 addrspace(270)* writeonly %i)
+// X86-LABEL: define dso_local void @test_sign_ext(%struct.Foo* %f, i32* writeonly %i)
 // X64: %{{.+}} = addrspacecast i32 addrspace(270)* %i to i32*
 // X86: %{{.+}} = addrspacecast i32* %i to i32 addrspace(272)*
   f->p64 = i;
   use_foo(f);
 }
 void test_zero_ext(struct Foo *f, int * __ptr32 __uptr i) {
-// X64-LABEL: define dso_local void @test_zero_ext({{.*}}i32 addrspace(271)* %i)
-// X86-LABEL: define dso_local void @test_zero_ext({{.*}}i32 addrspace(271)* %i)
+// X64-LABEL: define dso_local void @test_zero_ext({{.*}}i32 addrspace(271)* writeonly %i)
+// X86-LABEL: define dso_local void @test_zero_ext({{.*}}i32 addrspace(271)* writeonly %i)
 // X64: %{{.+}} = addrspacecast i32 addrspace(271)* %i to i32*
 // X86: %{{.+}} = addrspacecast i32 addrspace(271)* %i to i32 addrspace(272)*
   f->p64 = i;
   use_foo(f);
 }
 void test_trunc(struct Foo *f, int * __ptr64 i) {
-// X64-LABEL: define dso_local void @test_trunc(%struct.Foo* %f, i32* %i)
-// X86-LABEL: define dso_local void @test_trunc({{.*}}i32 addrspace(272)* %i)
+// X64-LABEL: define dso_local void @test_trunc(%struct.Foo* %f, i32* writeonly %i)
+// X86-LABEL: define dso_local void @test_trunc({{.*}}i32 addrspace(272)* writeonly %i)
 // X64: %{{.+}} = addrspacecast i32* %i to i32 addrspace(270)*
 // X86: %{{.+}} = addrspacecast i32 addrspace(272)* %i to i32*
   f->p32 = i;
   use_foo(f);
 }
 void test_noop(struct Foo *f, int * __ptr32 i) {
-// X64-LABEL: define dso_local void @test_noop({{.*}}i32 addrspace(270)* %i)
-// X86-LABEL: define dso_local void @test_noop({{.*}}i32* %i)
+// X64-LABEL: define dso_local void @test_noop({{.*}}i32 addrspace(270)* writeonly %i)
+// X86-LABEL: define dso_local void @test_noop({{.*}}i32* writeonly %i)
 // X64-NOT: addrspacecast
 // X86-NOT: addrspacecast
   f->p32 = i;
@@ -40,8 +40,8 @@
 }
 
 void test_other(struct Foo *f, __attribute__((address_space(10))) int *i) {
-// X64-LABEL: define dso_local void @test_other({{.*}}i32 addrspace(10)* %i)
-// X86-LABEL: define dso_local void @test_other({{.*}}i32 addrspace(10)* %i)
+// X64-LABEL: define dso_local void @test_other({{.*}}i32 addrspace(10)* writeonly %i)
+// X86-LABEL: define dso_local void @test_other({{.*}}i32 addrspace(10)* writeonly %i)
 // X64: %{{.+}} = addrspacecast i32 addrspace(10)* %i to i32 addrspace(270)*
 // X86: %{{.+}} = addrspacecast i32 addrspace(10)* %i to i32*
   f->p32 = (int * __ptr32)i;
diff --git a/clang/test/CodeGenOpenCL/amdgpu-abi-struct-coerce.cl b/clang/test/CodeGenOpenCL/amdgpu-abi-struct-coerce.cl
--- a/clang/test/CodeGenOpenCL/amdgpu-abi-struct-coerce.cl
+++ b/clang/test/CodeGenOpenCL/amdgpu-abi-struct-coerce.cl
@@ -439,7 +439,7 @@
   return s;
 }
 
-// CHECK: define{{.*}} void @func_flexible_array_ret(%struct.flexible_array addrspace(5)* noalias nocapture sret(%struct.flexible_array) align 4 %agg.result)
+// CHECK: define{{.*}} void @func_flexible_array_ret(%struct.flexible_array addrspace(5)* noalias nocapture writeonly sret(%struct.flexible_array) align 4 %agg.result)
 flexible_array func_flexible_array_ret()
 {
   flexible_array s = { 0 };
diff --git a/clang/test/CodeGenOpenCL/amdgpu-call-kernel.cl b/clang/test/CodeGenOpenCL/amdgpu-call-kernel.cl
--- a/clang/test/CodeGenOpenCL/amdgpu-call-kernel.cl
+++ b/clang/test/CodeGenOpenCL/amdgpu-call-kernel.cl
@@ -1,6 +1,6 @@
 // REQUIRES: amdgpu-registered-target
 // RUN: %clang_cc1 -triple amdgcn-unknown-unknown -S -emit-llvm -o - %s | FileCheck %s
-// CHECK: define{{.*}} amdgpu_kernel void @test_call_kernel(i32 addrspace(1)* nocapture %out)
+// CHECK: define{{.*}} amdgpu_kernel void @test_call_kernel(i32 addrspace(1)* nocapture writeonly %out)
 // CHECK: store i32 4, i32 addrspace(1)* %out, align 4
 
 kernel void test_kernel(global int *out)
diff --git a/clang/test/CodeGenOpenCL/kernels-have-spir-cc-by-default.cl b/clang/test/CodeGenOpenCL/kernels-have-spir-cc-by-default.cl
--- a/clang/test/CodeGenOpenCL/kernels-have-spir-cc-by-default.cl
+++ b/clang/test/CodeGenOpenCL/kernels-have-spir-cc-by-default.cl
@@ -28,7 +28,7 @@
 // CHECK: spir_kernel
 // AMDGCN: define{{.*}} amdgpu_kernel void @test_single
 // CHECK: struct.int_single* nocapture {{.*}} byval(%struct.int_single)
-// CHECK: i32* nocapture %output
+// CHECK: i32* nocapture writeonly %output
  output[0] = input.a;
 }
 
@@ -36,7 +36,7 @@
 // CHECK: spir_kernel
 // AMDGCN: define{{.*}} amdgpu_kernel void @test_pair
 // CHECK: struct.int_pair* nocapture {{.*}} byval(%struct.int_pair)
-// CHECK: i32* nocapture %output
+// CHECK: i32* nocapture writeonly %output
  output[0] = (int)input.a;
  output[1] = (int)input.b;
 }
@@ -45,7 +45,7 @@
 // CHECK: spir_kernel
 // AMDGCN: define{{.*}} amdgpu_kernel void @test_kernel
 // CHECK: struct.test_struct* nocapture {{.*}} byval(%struct.test_struct)
-// CHECK: i32* nocapture %output
+// CHECK: i32* nocapture writeonly %output
  output[0] = input.elementA;
  output[1] = input.elementB;
  output[2] = (int)input.elementC;
@@ -59,7 +59,7 @@
 void test_function(int_pair input, global int* output) {
 // CHECK-NOT: spir_kernel
 // AMDGCN-NOT: define{{.*}} amdgpu_kernel void @test_function
-// CHECK: i64 %input.coerce0, i64 %input.coerce1, i32* nocapture %output
+// CHECK: i64 %input.coerce0, i64 %input.coerce1, i32* nocapture writeonly %output
  output[0] = (int)input.a;
  output[1] = (int)input.b;
 }
diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -76,6 +76,7 @@
 STATISTIC(NumReturned, "Number of arguments marked returned");
 STATISTIC(NumReadNoneArg, "Number of arguments marked readnone");
 STATISTIC(NumReadOnlyArg, "Number of arguments marked readonly");
+STATISTIC(NumWriteOnlyArg, "Number of arguments marked writeonly");
 STATISTIC(NumNoAlias, "Number of function returns marked noalias");
 STATISTIC(NumNonNullReturn, "Number of function returns marked nonnull");
 STATISTIC(NumNoRecurse, "Number of functions marked as norecurse");
@@ -649,8 +650,8 @@
 
 /// Returns Attribute::None, Attribute::ReadOnly or Attribute::ReadNone.
 static Attribute::AttrKind
-determinePointerReadAttrs(Argument *A,
-                          const SmallPtrSet<Argument *, 8> &SCCNodes) {
+determinePointerAccessAttrs(Argument *A,
+                            const SmallPtrSet<Argument *, 8> &SCCNodes) {
   SmallVector<Use *, 32> Worklist;
   SmallPtrSet<Use *, 32> Visited;
 
@@ -659,7 +660,7 @@
     return Attribute::None;
 
   bool IsRead = false;
-  // We don't need to track IsWritten. If A is written to, return immediately.
+  bool IsWrite = false;
 
   for (Use &U : A->uses()) {
     Visited.insert(&U);
@@ -667,6 +668,10 @@
   }
 
   while (!Worklist.empty()) {
+    if (IsWrite && IsRead)
+      // No point in searching further..
+      return Attribute::None;
+
     Use *U = Worklist.pop_back_val();
     Instruction *I = cast<Instruction>(U->getUser());
 
@@ -763,6 +768,15 @@
       IsRead = true;
       break;
 
+    case Instruction::Store:
+      // A volatile store has side effects beyond what writeonly can be relied
+      // upon.
+      if (cast<StoreInst>(I)->isVolatile())
+        return Attribute::None;
+
+      IsWrite = true;
+      break;
+
     case Instruction::ICmp:
     case Instruction::Ret:
       break;
@@ -772,7 +786,14 @@
     }
   }
 
-  return IsRead ? Attribute::ReadOnly : Attribute::ReadNone;
+  if (IsWrite && IsRead)
+    return Attribute::None;
+  else if (IsRead)
+    return Attribute::ReadOnly;
+  else if (IsWrite)
+    return Attribute::WriteOnly;
+  else
+    return Attribute::ReadNone;
 }
 
 /// Deduce returned attributes for the SCC.
@@ -865,9 +886,10 @@
   return Changed;
 }
 
-static bool addReadAttr(Argument *A, Attribute::AttrKind R) {
-  assert((R == Attribute::ReadOnly || R == Attribute::ReadNone)
-         && "Must be a Read attribute.");
+static bool addAccessAttr(Argument *A, Attribute::AttrKind R) {
+  assert((R == Attribute::ReadOnly || R == Attribute::ReadNone ||
+          R == Attribute::WriteOnly)
+         && "Must be an access attribute.");
   assert(A && "Argument must not be null.");
 
   // If the argument already has the attribute, nothing needs to be done.
@@ -880,7 +902,12 @@
   A->removeAttr(Attribute::ReadOnly);
   A->removeAttr(Attribute::ReadNone);
   A->addAttr(R);
-  R == Attribute::ReadOnly ? ++NumReadOnlyArg : ++NumReadNoneArg;
+  if (R == Attribute::ReadOnly)
+    ++NumReadOnlyArg;
+  else if (R == Attribute::WriteOnly)
+    ++NumWriteOnlyArg;
+  else
+    ++NumReadNoneArg;
   return true;
 }
 
@@ -945,15 +972,15 @@
         // Otherwise, it's captured. Don't bother doing SCC analysis on it.
       }
       if (!HasNonLocalUses && !A->onlyReadsMemory()) {
-        // Can we determine that it's readonly/readnone without doing an SCC?
-        // Note that we don't allow any calls at all here, or else our result
-        // will be dependent on the iteration order through the functions in the
-        // SCC.
+        // Can we determine that it's readonly/readnone/writeonly without doing
+        // an SCC? Note that we don't allow any calls at all here, or else our
+        // result will be dependent on the iteration order through the
+        // functions in the SCC.
         SmallPtrSet<Argument *, 8> Self;
         Self.insert(&*A);
-        Attribute::AttrKind R = determinePointerReadAttrs(&*A, Self);
+        Attribute::AttrKind R = determinePointerAccessAttrs(&*A, Self);
         if (R != Attribute::None)
-          if (addReadAttr(A, R))
+          if (addAccessAttr(A, R))
             Changed.insert(F);
       }
     }
@@ -1023,10 +1050,10 @@
       Changed.insert(A->getParent());
     }
 
-    // We also want to compute readonly/readnone. With a small number of false
-    // negatives, we can assume that any pointer which is captured isn't going
-    // to be provably readonly or readnone, since by definition we can't
-    // analyze all uses of a captured pointer.
+    // We also want to compute readonly/readnone/writeonly. With a small number
+    // of false negatives, we can assume that any pointer which is captured
+    // isn't going to be provably readonly or readnone, since by definition
+    // we can't analyze all uses of a captured pointer.
     //
     // The false negatives happen when the pointer is captured by a function
     // that promises readonly/readnone behaviour on the pointer, then the
@@ -1034,24 +1061,28 @@
     // Also, a readonly/readnone pointer may be returned, but returning a
     // pointer is capturing it.
 
-    Attribute::AttrKind ReadAttr = Attribute::ReadNone;
-    for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) {
+    auto meetAccessAttr = [](Attribute::AttrKind A, Attribute::AttrKind B) {
+      if (A == B)
+        return A;
+      if (A == Attribute::ReadNone)
+        return B;
+      if (B == Attribute::ReadNone)
+        return A;
+      return Attribute::None;
+    };
+
+    Attribute::AttrKind AccessAttr = Attribute::ReadNone;
+    for (unsigned i = 0, e = ArgumentSCC.size();
+         i != e && AccessAttr != Attribute::None; ++i) {
       Argument *A = ArgumentSCC[i]->Definition;
-      Attribute::AttrKind K = determinePointerReadAttrs(A, ArgumentSCCNodes);
-      if (K == Attribute::ReadNone)
-        continue;
-      if (K == Attribute::ReadOnly) {
-        ReadAttr = Attribute::ReadOnly;
-        continue;
-      }
-      ReadAttr = K;
-      break;
+      Attribute::AttrKind K = determinePointerAccessAttrs(A, ArgumentSCCNodes);
+      AccessAttr = meetAccessAttr(AccessAttr, K);
     }
 
-    if (ReadAttr != Attribute::None) {
+    if (AccessAttr != Attribute::None) {
       for (unsigned i = 0, e = ArgumentSCC.size(); i != e; ++i) {
         Argument *A = ArgumentSCC[i]->Definition;
-        if (addReadAttr(A, ReadAttr))
+        if (addAccessAttr(A, AccessAttr))
           Changed.insert(A->getParent());
       }
     }
diff --git a/llvm/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll b/llvm/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
--- a/llvm/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
+++ b/llvm/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
@@ -15,7 +15,7 @@
   ret void
 }
 
-; CHECK: define void @test0_no(i32* nocapture %p) #1 {
+; CHECK: define void @test0_no(i32* nocapture writeonly %p) #1 {
 define void @test0_no(i32* %p) nounwind {
   store i32 0, i32* %p, !tbaa !2
   ret void
diff --git a/llvm/test/Feature/OperandBundles/pr26510.ll b/llvm/test/Feature/OperandBundles/pr26510.ll
--- a/llvm/test/Feature/OperandBundles/pr26510.ll
+++ b/llvm/test/Feature/OperandBundles/pr26510.ll
@@ -10,7 +10,7 @@
 
 declare void @foo() readnone
 
-; CHECK-LABEL: define i8* @test(i8* %p)
+; CHECK-LABEL: define i8* @test(i8* writeonly %p)
 ; CHECK:   %a = alloca i8*, align 8
 ; CHECK:   store i8* %p, i8** %a, align 8
 ; CHECK:   call void @foo() [ "abc"(i8** %a) ]
diff --git a/llvm/test/Transforms/Coroutines/coro-async.ll b/llvm/test/Transforms/Coroutines/coro-async.ll
--- a/llvm/test/Transforms/Coroutines/coro-async.ll
+++ b/llvm/test/Transforms/Coroutines/coro-async.ll
@@ -256,7 +256,7 @@
   unreachable
 }
 
-; CHECK-LABEL: define swiftcc void @my_async_function2(%async.task* %task, %async.actor* %actor, i8* %async.ctxt)
+; CHECK-LABEL: define swiftcc void @my_async_function2(%async.task* %task, %async.actor* %actor, i8* writeonly %async.ctxt)
 ; CHECK-SAME: #[[FRAMEPOINTER:[0-9]+]]
 ; CHECK-SAME: !dbg ![[SP3:[0-9]+]]
 ; CHECK: store i8* %async.ctxt,
@@ -269,7 +269,7 @@
 ; CHECK: tail call swiftcc void @asyncSuspend(i8* [[CALLEE_CTXT]], %async.task* %task, %async.actor* %actor)
 ; CHECK: ret void
 
-; CHECK-LABEL: define internal swiftcc void @my_async_function2.resume.0(i8* %0, i8* nocapture readnone %1, i8* nocapture readonly %2)
+; CHECK-LABEL: define internal swiftcc void @my_async_function2.resume.0(i8* writeonly %0, i8* nocapture readnone %1, i8* nocapture readonly %2)
 ; CHECK-SAME: #[[FRAMEPOINTER]]
 ; CHECK-SAME: !dbg ![[SP4:[0-9]+]]
 ; CHECK: [[CALLEE_CTXT_ADDR:%.*]] = bitcast i8* %2 to i8**
diff --git a/llvm/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll b/llvm/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll
--- a/llvm/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll
+++ b/llvm/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll
@@ -7,7 +7,7 @@
 	ret i32* %tmp
 }
 
-; CHECK: define i32* @b(i32* %q)
+; CHECK: define i32* @b(i32* writeonly %q)
 define i32* @b(i32 *%q) {
 	%mem = alloca i32*
 	store i32* %q, i32** %mem
diff --git a/llvm/test/Transforms/FunctionAttrs/nocapture.ll b/llvm/test/Transforms/FunctionAttrs/nocapture.ll
--- a/llvm/test/Transforms/FunctionAttrs/nocapture.ll
+++ b/llvm/test/Transforms/FunctionAttrs/nocapture.ll
@@ -8,7 +8,7 @@
 	ret i32* %q
 }
 
-; FNATTR: define void @c2(i32* %q)
+; FNATTR: define void @c2(i32* writeonly %q)
 ; It would also be acceptable to mark %q as readnone. Update @c3 too.
 define void @c2(i32* %q) {
 	store i32* %q, i32** @g
@@ -259,7 +259,7 @@
   ret void
 }
 
-; FNATTR: @nocaptureStrip(i8* nocapture %p)
+; FNATTR: @nocaptureStrip(i8* nocapture writeonly %p)
 define void @nocaptureStrip(i8* %p) {
 entry:
   %b = call i8* @llvm.strip.invariant.group.p0i8(i8* %p)
@@ -268,7 +268,7 @@
 }
 
 @g3 = global i8* null
-; FNATTR: define void @captureStrip(i8* %p)
+; FNATTR: define void @captureStrip(i8* writeonly %p)
 define void @captureStrip(i8* %p) {
   %b = call i8* @llvm.strip.invariant.group.p0i8(i8* %p)
   store i8* %b, i8** @g3
diff --git a/llvm/test/Transforms/FunctionAttrs/readattrs.ll b/llvm/test/Transforms/FunctionAttrs/readattrs.ll
--- a/llvm/test/Transforms/FunctionAttrs/readattrs.ll
+++ b/llvm/test/Transforms/FunctionAttrs/readattrs.ll
@@ -34,7 +34,7 @@
   ret void
 }
 
-; CHECK: define void @test5(i8** nocapture %p, i8* %q)
+; CHECK: define void @test5(i8** nocapture writeonly %p, i8* writeonly %q)
 ; Missed optz'n: we could make %q readnone, but don't break test6!
 define void @test5(i8** %p, i8* %q) {
   store i8* %q, i8** %p
@@ -42,7 +42,7 @@
 }
 
 declare void @test6_1()
-; CHECK: define void @test6_2(i8** nocapture %p, i8* %q)
+; CHECK: define void @test6_2(i8** nocapture writeonly %p, i8* writeonly %q)
 ; This is not a missed optz'n.
 define void @test6_2(i8** %p, i8* %q) {
   store i8* %q, i8** %p
@@ -68,7 +68,7 @@
   ret i32* %p
 }
 
-; CHECK: define void @test8_2(i32* %p)
+; CHECK: define void @test8_2(i32* writeonly %p)
 define void @test8_2(i32* %p) {
 entry:
   %call = call i32* @test8_1(i32* %p)
diff --git a/llvm/test/Transforms/FunctionAttrs/writeonly.ll b/llvm/test/Transforms/FunctionAttrs/writeonly.ll
--- a/llvm/test/Transforms/FunctionAttrs/writeonly.ll
+++ b/llvm/test/Transforms/FunctionAttrs/writeonly.ll
@@ -25,13 +25,13 @@
   ret void
 }
 
-; CHECK: define void @test_store(i8* nocapture %p)
+; CHECK: define void @test_store(i8* nocapture writeonly %p)
 define void @test_store(i8* %p) {
   store i8 0, i8* %p
   ret void
 }
 
-; CHECK: define void @test_addressing(i8* nocapture %p)
+; CHECK: define void @test_addressing(i8* nocapture writeonly %p)
 define void @test_addressing(i8* %p) {
   %gep = getelementptr i8, i8* %p, i64 8
   %bitcast = bitcast i8* %gep to i32*