Index: llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h
===================================================================
--- llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h
+++ llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h
@@ -138,6 +138,10 @@
   /// Create a static initializer for our data, on platforms that need it,
   /// and for any profile output file that was specified.
   void emitInitialization();
+
+  /// Check if our target supports 8 byte/ 64 bit Atomics. Don't use
+  /// them if it doesn't.
+  bool targetSupportsAtomic() const;
 };
 
 } // end namespace llvm
Index: llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -454,6 +454,9 @@
 }
 
 bool InstrProfiling::isCounterPromotionEnabled() const {
+  if (!targetSupportsAtomic())
+    return false;
+
   if (DoCounterPromotion.getNumOccurrences() > 0)
     return DoCounterPromotion;
 
@@ -737,8 +740,9 @@
   auto *Addr = getCounterAddress(Inc);
 
   IRBuilder<> Builder(Inc);
-  if (Options.Atomic || AtomicCounterUpdateAll ||
-      (Inc->getIndex()->isZeroValue() && AtomicFirstCounter)) {
+  if (targetSupportsAtomic() &&
+      (Options.Atomic || AtomicCounterUpdateAll ||
+       (Inc->getIndex()->isZeroValue() && AtomicFirstCounter))) {
     Builder.CreateAtomicRMW(AtomicRMWInst::Add, Addr, Inc->getStep(),
                             MaybeAlign(), AtomicOrdering::Monotonic);
   } else {
@@ -1376,3 +1380,12 @@
 
   appendToGlobalCtors(*M, F, 0);
 }
+
+bool InstrProfiling::targetSupportsAtomic() const {
+  // As far as I can tell, we don't have access to specific enough target
+  // details here to really know if they support the atomic add or not. It seems
+  // like a safe assumption though that only 64 bit targets will support the 64
+  // bit atomic operation we're going to inject.
+  // If this assumption is incorrect, additional logic can be added here.
+  return TT.isArch64Bit();
+}
Index: llvm/test/Instrumentation/InstrProfiling/atomic-updates-disabled.ll
===================================================================
--- /dev/null
+++ llvm/test/Instrumentation/InstrProfiling/atomic-updates-disabled.ll
@@ -0,0 +1,16 @@
+; RUN: opt < %s -S -passes=instrprof -instrprof-atomic-counter-update-all | FileCheck %s
+; This test purposely uses a target triple that doesn't support the atomic update used by InstrProf
+; It shouldn't end up with an atomic update instruction
+
+target triple = "mips-unknown-linux-gnu"
+
+@__profn_foo = private constant [3 x i8] c"foo"
+
+; CHECK-LABEL: define void @foo
+; CHECK-NOT: atomicrmw add ptr @__profc_foo, i64 1 monotonic
+define void @foo() {
+  call void @llvm.instrprof.increment(ptr @__profn_foo, i64 0, i32 1, i32 0)
+  ret void
+}
+
+declare void @llvm.instrprof.increment(ptr, i64, i32, i32)
Index: llvm/test/Instrumentation/InstrProfiling/atomic-updates.ll
===================================================================
--- llvm/test/Instrumentation/InstrProfiling/atomic-updates.ll
+++ llvm/test/Instrumentation/InstrProfiling/atomic-updates.ll
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -S -passes=instrprof -instrprof-atomic-counter-update-all | FileCheck %s
+; This test purposely uses a target triple that does support the atomic update used by InstrProf
 
 target triple = "x86_64-apple-macosx10.10.0"
 
Index: llvm/test/Transforms/PGOProfile/counter_promo.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/counter_promo.ll
+++ llvm/test/Transforms/PGOProfile/counter_promo.ll
@@ -1,6 +1,8 @@
 ; RUN: opt < %s --passes=pgo-instr-gen,instrprof -do-counter-promotion=true -skip-ret-exit-block=0 -S | FileCheck --check-prefix=PROMO --check-prefix=NONATOMIC_PROMO %s
 ; RUN: opt < %s --passes=pgo-instr-gen,instrprof -do-counter-promotion=true -atomic-counter-update-promoted -skip-ret-exit-block=0 -S | FileCheck --check-prefix=PROMO --check-prefix=ATOMIC_PROMO %s
 
+target triple = "x86_64-apple-macosx10.10.0"
+
 define void @foo(i32 %n, i32 %N) {
 ; PROMO-LABEL: @foo
 ; PROMO: {{.*}} = load {{.*}} @__profc_foo{{.*}} 3)
Index: llvm/test/Transforms/PGOProfile/counter_promo_exit_merge.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/counter_promo_exit_merge.ll
+++ llvm/test/Transforms/PGOProfile/counter_promo_exit_merge.ll
@@ -1,5 +1,7 @@
 ; RUN: opt < %s --passes=instrprof -do-counter-promotion=true -speculative-counter-promotion-max-exiting=3 -S | FileCheck --check-prefix=PROMO %s
 
+target triple = "x86_64-apple-macosx10.10.0"
+
 $__llvm_profile_raw_version = comdat any
 
 @g = common local_unnamed_addr global i32 0, align 4
Index: llvm/test/Transforms/PGOProfile/counter_promo_mexits.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/counter_promo_mexits.ll
+++ llvm/test/Transforms/PGOProfile/counter_promo_mexits.ll
@@ -1,5 +1,7 @@
 ; RUN: opt < %s --passes=pgo-instr-gen,instrprof -do-counter-promotion=true -speculative-counter-promotion-max-exiting=3 -S | FileCheck --check-prefix=PROMO %s
 
+target triple = "x86_64-apple-macosx10.10.0"
+
 @g = common local_unnamed_addr global i32 0, align 4
 
 define void @foo(i32 %arg) local_unnamed_addr {
Index: llvm/test/Transforms/PGOProfile/counter_promo_nest-inseltpoison.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/counter_promo_nest-inseltpoison.ll
+++ llvm/test/Transforms/PGOProfile/counter_promo_nest-inseltpoison.ll
@@ -1,6 +1,8 @@
 ; TEST that counter updates are promoted outside the whole loop nest
 ; RUN: opt < %s --passes=pgo-instr-gen,instrprof -do-counter-promotion=true -S | FileCheck --check-prefix=PROMO  %s 
 
+target triple = "x86_64-apple-macosx10.10.0"
+
 @g = common local_unnamed_addr global i32 0, align 4
 @c = local_unnamed_addr global i32 10, align 4
 
Index: llvm/test/Transforms/PGOProfile/counter_promo_nest.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/counter_promo_nest.ll
+++ llvm/test/Transforms/PGOProfile/counter_promo_nest.ll
@@ -1,6 +1,8 @@
 ; TEST that counter updates are promoted outside the whole loop nest
 ; RUN: opt < %s --passes=pgo-instr-gen,instrprof -do-counter-promotion=true -S | FileCheck --check-prefix=PROMO  %s 
 
+target triple = "x86_64-apple-macosx10.10.0"
+
 @g = common local_unnamed_addr global i32 0, align 4
 @c = local_unnamed_addr global i32 10, align 4
 
Index: llvm/test/Transforms/PGOProfile/not_promote_ret_exit.ll
===================================================================
--- llvm/test/Transforms/PGOProfile/not_promote_ret_exit.ll
+++ llvm/test/Transforms/PGOProfile/not_promote_ret_exit.ll
@@ -1,6 +1,8 @@
 ; RUN: opt < %s -passes=instrprof -S -do-counter-promotion=1 -skip-ret-exit-block=1 | FileCheck %s --check-prefixes=CHECK,SKIP
 ; RUN: opt < %s -passes=instrprof -S -do-counter-promotion=1 -skip-ret-exit-block=0 | FileCheck %s --check-prefixes=CHECK,NOTSKIP
 
+target triple = "x86_64-apple-macosx10.10.0"
+
 $__llvm_profile_raw_version = comdat any
 
 @bar = dso_local local_unnamed_addr global i32 0, align 4