Index: lib/Target/ARM/ARMTargetTransformInfo.h
===================================================================
--- lib/Target/ARM/ARMTargetTransformInfo.h
+++ lib/Target/ARM/ARMTargetTransformInfo.h
@@ -41,6 +41,9 @@
       : BaseT(TM, F.getParent()->getDataLayout()), ST(TM->getSubtargetImpl(F)),
         TLI(ST->getTargetLowering()) {}
 
+  bool areInlineCompatible(const Function *Caller,
+                           const Function *Callee) const;
+
   bool enableInterleavedAccessVectorization() { return true; }
 
   /// Floating-point computation using ARMv8 AArch32 Advanced
Index: lib/Target/ARM/ARMTargetTransformInfo.cpp
===================================================================
--- lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -15,6 +15,22 @@
 
 #define DEBUG_TYPE "armtti"
 
+bool ARMTTIImpl::areInlineCompatible(const Function *Caller,
+                                     const Function *Callee) const {
+  const TargetMachine &TM = getTLI()->getTargetMachine();
+
+  const FeatureBitset &CallerBits =
+      TM.getSubtargetImpl(*Caller)->getFeatureBits();
+  const FeatureBitset &CalleeBits =
+      TM.getSubtargetImpl(*Callee)->getFeatureBits();
+  const FeatureBitset ThumbMode(ARM::ModeThumb);
+
+  // Inline a callee if the mode matches and the remaining target-features are a
+  // subset of the callers target-features.
+  return CallerBits[ARM::ModeThumb] == CalleeBits[ARM::ModeThumb] &&
+         ((CallerBits & CalleeBits) | ThumbMode) == (CalleeBits | ThumbMode);
+}
+
 int ARMTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
   assert(Ty->isIntegerTy());
 
Index: test/Transforms/Inline/ARM/inline-target-attr.ll
===================================================================
--- /dev/null
+++ test/Transforms/Inline/ARM/inline-target-attr.ll
@@ -0,0 +1,51 @@
+; RUN: opt < %s -mtriple=arm-unknown-linux-gnu -S -inline | FileCheck %s
+; RUN: opt < %s -mtriple=arm-unknown-linux-gnu -S -passes='cgscc(inline)' | FileCheck %s
+; Check that we only inline when we have compatible target attributes.
+; ARM has implemented a target attribute that will verify that the attribute
+; sets are compatible.
+
+define i32 @foo() #0 {
+entry:
+  %call = call i32 (...) @baz()
+  ret i32 %call
+; CHECK-LABEL: foo
+; CHECK: call i32 (...) @baz()
+}
+declare i32 @baz(...) #0
+
+define i32 @bar() #1 {
+entry:
+  %call = call i32 @foo()
+  ret i32 %call
+; CHECK-LABEL: bar
+; CHECK: call i32 (...) @baz()
+}
+
+define i32 @qux() #0 {
+entry:
+  %call = call i32 @bar()
+  ret i32 %call
+; CHECK-LABEL: qux
+; CHECK: call i32 @bar()
+}
+
+define i32 @thumb_fn() #2 {
+entry:
+  %call = call i32 @foo()
+  ret i32 %call
+; CHECK-LABEL: thumb_fn
+; CHECK: call i32 @foo
+}
+
+define i32 @strict_align() #3 {
+entry:
+  %call = call i32 @foo()
+  ret i32 %call
+; CHECK-LABEL: strict_align
+; CHECK: call i32 (...) @baz()
+}
+
+attributes #0 = { "target-cpu"="generic" "target-features"="+dsp,+neon" }
+attributes #1 = { "target-cpu"="generic" "target-features"="+dsp,+neon,+fp16" }
+attributes #2 = { "target-cpu"="generic" "target-features"="+dsp,+neon,+fp16,+thumb-mode" }
+attributes #3 = { "target-cpu"="generic" "target-features"="+dsp,+neon,+strict-align" }
Index: test/Transforms/Inline/ARM/lit.local.cfg
===================================================================
--- /dev/null
+++ test/Transforms/Inline/ARM/lit.local.cfg
@@ -0,0 +1,2 @@
+if not 'ARM' in config.root.targets:
+    config.unsupported = True