Index: llvm/lib/Transforms/IPO/AttributorAttributes.cpp
===================================================================
--- llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -2427,7 +2427,20 @@
 
   /// See AbstractAttribute::updateImpl(...).
   ChangeStatus updateImpl(Attributor &A) override {
-    // TODO: Implement this.
+    // If an associated value is an local global variable and it is used only once, 
+    // we can deduce noalias for it.
+    if (auto *GV = dyn_cast<GlobalVariable>(&getAssociatedValue())) {
+      if (GV->hasLocalLinkage()) {
+        int LiveUseCount = 0;
+        auto UsePred = [&](const Use &U, bool &) {
+          LiveUseCount++;
+          return LiveUseCount <= 1;
+        };
+        if (A.checkForAllUses(UsePred, *this, getAssociatedValue())) {
+          return ChangeStatus::UNCHANGED;
+        }
+      }
+    }
     return indicatePessimisticFixpoint();
   }
 
Index: llvm/test/Transforms/Attributor/ArgumentPromotion/variadic.ll
===================================================================
--- llvm/test/Transforms/Attributor/ArgumentPromotion/variadic.ll
+++ llvm/test/Transforms/Attributor/ArgumentPromotion/variadic.ll
@@ -21,7 +21,7 @@
 ; CHECK-LABEL: define {{[^@]+}}@main
 ; CHECK-SAME: (i32 [[ARGC:%.*]], i8** nocapture nofree readnone [[ARGV:%.*]]) {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    tail call void (i8*, i8*, i8*, i8*, i8*, ...) @callee_t0f(i8* undef, i8* undef, i8* undef, i8* undef, i8* undef, %struct.tt0* noundef nonnull byval align 8 dereferenceable(16) @t45)
+; CHECK-NEXT:    tail call void (i8*, i8*, i8*, i8*, i8*, ...) @callee_t0f(i8* undef, i8* undef, i8* undef, i8* undef, i8* undef, %struct.tt0* noalias noundef nonnull byval align 8 dereferenceable(16) @t45)
 ; CHECK-NEXT:    ret i32 0
 ;
 entry:
Index: llvm/test/Transforms/Attributor/IPConstantProp/2009-09-24-byval-ptr.ll
===================================================================
--- llvm/test/Transforms/Attributor/IPConstantProp/2009-09-24-byval-ptr.ll
+++ llvm/test/Transforms/Attributor/IPConstantProp/2009-09-24-byval-ptr.ll
@@ -106,7 +106,7 @@
 ; IS__TUNIT_OPM-LABEL: define {{[^@]+}}@unions
 ; IS__TUNIT_OPM-SAME: () [[ATTR1:#.*]] {
 ; IS__TUNIT_OPM-NEXT:  entry:
-; IS__TUNIT_OPM-NEXT:    [[RESULT:%.*]] = call i32 @vfu2(%struct.MYstr* nocapture nofree noundef nonnull readonly byval align 8 dereferenceable(8) @mystr) [[ATTR0]]
+; IS__TUNIT_OPM-NEXT:    [[RESULT:%.*]] = call i32 @vfu2(%struct.MYstr* noalias nocapture nofree noundef nonnull readonly byval align 8 dereferenceable(8) @mystr) [[ATTR0]]
 ; IS__TUNIT_OPM-NEXT:    ret i32 [[RESULT]]
 ;
 ; IS__TUNIT_NPM: Function Attrs: nofree nosync nounwind willreturn
@@ -217,7 +217,7 @@
 ; IS__TUNIT_OPM-LABEL: define {{[^@]+}}@unions_v2
 ; IS__TUNIT_OPM-SAME: () [[ATTR2]] {
 ; IS__TUNIT_OPM-NEXT:  entry:
-; IS__TUNIT_OPM-NEXT:    [[RESULT:%.*]] = call i32 @vfu2_v2(%struct.MYstr* nocapture nofree noundef nonnull readonly byval align 8 dereferenceable(8) @mystr) [[ATTR2]]
+; IS__TUNIT_OPM-NEXT:    [[RESULT:%.*]] = call i32 @vfu2_v2(%struct.MYstr* noalias nocapture nofree noundef nonnull readonly byval align 8 dereferenceable(8) @mystr) [[ATTR2]]
 ; IS__TUNIT_OPM-NEXT:    ret i32 [[RESULT]]
 ;
 ; IS__TUNIT_NPM: Function Attrs: nofree nosync nounwind readnone willreturn
Index: llvm/test/Transforms/Attributor/IPConstantProp/openmp_parallel_for.ll
===================================================================
--- llvm/test/Transforms/Attributor/IPConstantProp/openmp_parallel_for.ll
+++ llvm/test/Transforms/Attributor/IPConstantProp/openmp_parallel_for.ll
@@ -47,7 +47,7 @@
 ; IS__TUNIT_NPM-NEXT:    store i32 [[N]], i32* [[N_ADDR]], align 4
 ; IS__TUNIT_NPM-NEXT:    store float 3.000000e+00, float* [[P]], align 4
 ; IS__TUNIT_NPM-NEXT:    store i32 7, i32* [[N_ADDR]], align 4
-; IS__TUNIT_NPM-NEXT:    call void (%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(%struct.ident_t* noundef nonnull align 8 dereferenceable(24) [[GLOB1:@.*]], i32 noundef 3, void (i32*, i32*, ...)* noundef bitcast (void (i32*, i32*, i32*, float*, i64)* @.omp_outlined. to void (i32*, i32*, ...)*), i32* noalias nocapture noundef nonnull readonly align 4 dereferenceable(4) [[N_ADDR]], float* noalias nocapture noundef nonnull readonly align 4 dereferenceable(4) [[P]], i64 undef)
+; IS__TUNIT_NPM-NEXT:    call void (%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(%struct.ident_t* noalias noundef nonnull align 8 dereferenceable(24) [[GLOB1:@.*]], i32 noundef 3, void (i32*, i32*, ...)* noundef bitcast (void (i32*, i32*, i32*, float*, i64)* @.omp_outlined. to void (i32*, i32*, ...)*), i32* noalias nocapture noundef nonnull readonly align 4 dereferenceable(4) [[N_ADDR]], float* noalias nocapture noundef nonnull readonly align 4 dereferenceable(4) [[P]], i64 undef)
 ; IS__TUNIT_NPM-NEXT:    ret void
 ;
 ; IS__CGSCC_OPM-LABEL: define {{[^@]+}}@foo
@@ -69,7 +69,7 @@
 ; IS__CGSCC_NPM-NEXT:    store i32 [[N]], i32* [[N_ADDR]], align 4
 ; IS__CGSCC_NPM-NEXT:    store float 3.000000e+00, float* [[P]], align 4
 ; IS__CGSCC_NPM-NEXT:    store i32 7, i32* [[N_ADDR]], align 4
-; IS__CGSCC_NPM-NEXT:    call void (%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(%struct.ident_t* noundef nonnull align 8 dereferenceable(24) [[GLOB1:@.*]], i32 noundef 3, void (i32*, i32*, ...)* noundef bitcast (void (i32*, i32*, i32*, float*, i64)* @.omp_outlined. to void (i32*, i32*, ...)*), i32* noalias nocapture noundef nonnull readonly align 4 dereferenceable(4) [[N_ADDR]], float* noalias nocapture noundef nonnull readonly align 4 dereferenceable(4) [[P]], i64 noundef 4617315517961601024)
+; IS__CGSCC_NPM-NEXT:    call void (%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(%struct.ident_t* noalias noundef nonnull align 8 dereferenceable(24) [[GLOB1:@.*]], i32 noundef 3, void (i32*, i32*, ...)* noundef bitcast (void (i32*, i32*, i32*, float*, i64)* @.omp_outlined. to void (i32*, i32*, ...)*), i32* noalias nocapture noundef nonnull readonly align 4 dereferenceable(4) [[N_ADDR]], float* noalias nocapture noundef nonnull readonly align 4 dereferenceable(4) [[P]], i64 noundef 4617315517961601024)
 ; IS__CGSCC_NPM-NEXT:    ret void
 ;
 entry:
@@ -139,7 +139,7 @@
 ; IS________OPM-NEXT:    br label [[OMP_LOOP_EXIT:%.*]]
 ; IS________OPM:       omp.loop.exit:
 ; IS________OPM-NEXT:    [[TMP12:%.*]] = load i32, i32* [[DOTGLOBAL_TID_]], align 4
-; IS________OPM-NEXT:    call void @__kmpc_for_static_fini(%struct.ident_t* noundef nonnull align 8 dereferenceable(24) [[GLOB0]], i32 [[TMP12]])
+; IS________OPM-NEXT:    call void @__kmpc_for_static_fini(%struct.ident_t* noalias noundef nonnull align 8 dereferenceable(24) [[GLOB0]], i32 [[TMP12]])
 ; IS________OPM-NEXT:    br label [[OMP_PRECOND_END]]
 ; IS________OPM:       omp.precond.end:
 ; IS________OPM-NEXT:    ret void
@@ -164,7 +164,7 @@
 ; IS________NPM-NEXT:    store i32 1, i32* [[DOTOMP_STRIDE]], align 4
 ; IS________NPM-NEXT:    store i32 0, i32* [[DOTOMP_IS_LAST]], align 4
 ; IS________NPM-NEXT:    [[TMP5:%.*]] = load i32, i32* [[DOTGLOBAL_TID_]], align 4
-; IS________NPM-NEXT:    call void @__kmpc_for_static_init_4(%struct.ident_t* noundef nonnull align 8 dereferenceable(24) [[GLOB0:@.*]], i32 [[TMP5]], i32 noundef 34, i32* noundef nonnull align 4 dereferenceable(4) [[DOTOMP_IS_LAST]], i32* noundef nonnull align 4 dereferenceable(4) [[DOTOMP_LB]], i32* noundef nonnull align 4 dereferenceable(4) [[DOTOMP_UB]], i32* noundef nonnull align 4 dereferenceable(4) [[DOTOMP_STRIDE]], i32 noundef 1, i32 noundef 1)
+; IS________NPM-NEXT:    call void @__kmpc_for_static_init_4(%struct.ident_t* noalias noundef nonnull align 8 dereferenceable(24) [[GLOB0:@.*]], i32 [[TMP5]], i32 noundef 34, i32* noundef nonnull align 4 dereferenceable(4) [[DOTOMP_IS_LAST]], i32* noundef nonnull align 4 dereferenceable(4) [[DOTOMP_LB]], i32* noundef nonnull align 4 dereferenceable(4) [[DOTOMP_UB]], i32* noundef nonnull align 4 dereferenceable(4) [[DOTOMP_STRIDE]], i32 noundef 1, i32 noundef 1)
 ; IS________NPM-NEXT:    [[TMP6:%.*]] = load i32, i32* [[DOTOMP_UB]], align 4
 ; IS________NPM-NEXT:    [[CMP6:%.*]] = icmp sgt i32 [[TMP6]], [[SUB3]]
 ; IS________NPM-NEXT:    br i1 [[CMP6]], label [[COND_TRUE:%.*]], label [[COND_FALSE:%.*]]
@@ -200,7 +200,7 @@
 ; IS________NPM-NEXT:    br label [[OMP_LOOP_EXIT:%.*]]
 ; IS________NPM:       omp.loop.exit:
 ; IS________NPM-NEXT:    [[TMP12:%.*]] = load i32, i32* [[DOTGLOBAL_TID_]], align 4
-; IS________NPM-NEXT:    call void @__kmpc_for_static_fini(%struct.ident_t* noundef nonnull align 8 dereferenceable(24) [[GLOB0]], i32 [[TMP12]])
+; IS________NPM-NEXT:    call void @__kmpc_for_static_fini(%struct.ident_t* noalias noundef nonnull align 8 dereferenceable(24) [[GLOB0]], i32 [[TMP12]])
 ; IS________NPM-NEXT:    br label [[OMP_PRECOND_END]]
 ; IS________NPM:       omp.precond.end:
 ; IS________NPM-NEXT:    ret void
Index: llvm/test/Transforms/Attributor/misc_crash.ll
===================================================================
--- llvm/test/Transforms/Attributor/misc_crash.ll
+++ llvm/test/Transforms/Attributor/misc_crash.ll
@@ -41,7 +41,7 @@
 define internal void @func2a(i32* %0) {
 ; CHECK: Function Attrs: nofree nosync nounwind willreturn writeonly
 ; CHECK-LABEL: define {{[^@]+}}@func2a
-; CHECK-SAME: (i32* nocapture nofree nonnull writeonly align 4 dereferenceable(4) [[TMP0:%.*]]) [[ATTR1:#.*]] {
+; CHECK-SAME: (i32* noalias nocapture nofree nonnull writeonly align 4 dereferenceable(4) [[TMP0:%.*]]) [[ATTR1:#.*]] {
 ; CHECK-NEXT:    store i32 0, i32* @var2, align 4
 ; CHECK-NEXT:    ret void
 ;
@@ -51,7 +51,7 @@
 
 define i32 @func2() {
 ; CHECK-LABEL: define {{[^@]+}}@func2() {
-; CHECK-NEXT:    [[TMP1:%.*]] = tail call i32 (i32*, ...) bitcast (void (i32*)* @func2a to i32 (i32*, ...)*)(i32* noundef nonnull align 4 dereferenceable(4) @var2)
+; CHECK-NEXT:    [[TMP1:%.*]] = tail call i32 (i32*, ...) bitcast (void (i32*)* @func2a to i32 (i32*, ...)*)(i32* noalias noundef nonnull align 4 dereferenceable(4) @var2)
 ; CHECK-NEXT:    [[TMP2:%.*]] = load i32, i32* @var2, align 4
 ; CHECK-NEXT:    ret i32 [[TMP2]]
 ;
@@ -63,7 +63,7 @@
 define i32 @func3(i1 %false) {
 ; CHECK-LABEL: define {{[^@]+}}@func3
 ; CHECK-SAME: (i1 [[FALSE:%.*]]) {
-; CHECK-NEXT:    [[TMP1:%.*]] = tail call i32 (i32*, ...) bitcast (void (i32*)* @func2a to i32 (i32*, ...)*)(i32* noundef nonnull align 4 dereferenceable(4) @var2)
+; CHECK-NEXT:    [[TMP1:%.*]] = tail call i32 (i32*, ...) bitcast (void (i32*)* @func2a to i32 (i32*, ...)*)(i32* noalias noundef nonnull align 4 dereferenceable(4) @var2)
 ; CHECK-NEXT:    br i1 [[FALSE]], label [[USE_BB:%.*]], label [[RET_BB:%.*]]
 ; CHECK:       use_bb:
 ; CHECK-NEXT:    ret i32 [[TMP1]]