Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -2240,6 +2240,9 @@
     Backends are free to ignore the attribute if they don't need to support
     different maximum legal vector types or such information can be inferred by
     other attributes.
+  ``"nooutline"``
+    This attribute indicates that outlining passes should not modify the
+    function.
 
 Call Site Attributes
 ----------------------
Index: llvm/lib/CodeGen/MachineOutliner.cpp
===================================================================
--- llvm/lib/CodeGen/MachineOutliner.cpp
+++ llvm/lib/CodeGen/MachineOutliner.cpp
@@ -880,10 +880,13 @@
   // iterating over each Function in M.
   for (Function &F : M) {
 
-    // If there's nothing in F, then there's no reason to try and outline from
-    // it.
-    if (F.empty())
+    if (F.hasFnAttribute("nooutline")) {
+      LLVM_DEBUG({
+        dbgs() << "... Skipping function with nooutline attribute: "
+               << F.getName() << "\n";
+      });
       continue;
+    }
 
     // There's something in F. Check if it has a MachineFunction associated with
     // it.
Index: llvm/lib/Transforms/IPO/IROutliner.cpp
===================================================================
--- llvm/lib/Transforms/IPO/IROutliner.cpp
+++ llvm/lib/Transforms/IPO/IROutliner.cpp
@@ -2426,6 +2426,7 @@
     PreviouslyOutlined = false;
     unsigned StartIdx = IRSC.getStartIdx();
     unsigned EndIdx = IRSC.getEndIdx();
+    const Function &FnForCurrCand = *IRSC.getFunction();
 
     for (unsigned Idx = StartIdx; Idx <= EndIdx; Idx++)
       if (Outlined.contains(Idx)) {
@@ -2445,9 +2446,17 @@
     if (BBHasAddressTaken)
       continue;
 
-    if (IRSC.getFunction()->hasOptNone())
+    if (FnForCurrCand.hasOptNone())
       continue;
 
+    if (FnForCurrCand.hasFnAttribute("nooutline")) {
+      LLVM_DEBUG({
+        dbgs() << "... Skipping function with nooutline attribute: "
+               << FnForCurrCand.getName() << "\n";
+      });
+      continue;
+    }
+
     if (IRSC.front()->Inst->getFunction()->hasLinkOnceODRLinkage() &&
         !OutlineFromLinkODRs)
       continue;
Index: llvm/test/CodeGen/AArch64/machine-outliner-nooutline-attribute.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/machine-outliner-nooutline-attribute.mir
@@ -0,0 +1,42 @@
+# RUN: llc -mtriple=aarch64 -debug-only=machine-outliner -run-pass=machine-outliner -verify-machineinstrs %s -o - 2>&1 | FileCheck %s
+# REQUIRES: asserts
+
+# CHECK: ... Skipping function with nooutline attribute: no_outline
+# CHECK-NOT: ... Skipping function with nooutline attribute: baz
+# CHECK-NOT: OUTLINED
+
+--- |
+  define void @no_outline() #0 { unreachable }
+  define void @baz() { unreachable }
+  attributes #0 = { noredzone "nooutline" }
+...
+---
+
+name:            no_outline
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $w0, $lr, $w8
+    $sp = frame-setup SUBXri $sp, 32, 0
+    $fp = frame-setup ADDXri $sp, 16, 0
+  bb.1:
+    BL @baz, implicit-def dead $lr, implicit $sp
+    $w17 = ORRWri $wzr, 1
+    $w17 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 4
+    BL @baz, implicit-def dead $lr, implicit $sp
+    $w17 = ORRWri $wzr, 1
+    $w17 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 3
+    BL @baz, implicit-def dead $lr, implicit $sp
+    $w17 = ORRWri $wzr, 1
+    $w17 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 2
+    BL @baz, implicit-def dead $lr, implicit $sp
+    $w17 = ORRWri $wzr, 1
+    $w17 = ORRWri $wzr, 1
+    $w0 = ORRWri $wzr, 1
+  bb.2:
+    $fp, $lr = LDPXi $sp, 2
+    RET undef $lr
+
Index: llvm/test/Transforms/IROutliner/nooutline-attribute.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/IROutliner/nooutline-attribute.ll
@@ -0,0 +1,30 @@
+; RUN: opt -S -verify -debug-only=iroutliner -iroutliner -ir-outlining-no-cost %s -o - 2>&1 | FileCheck %s
+; REQUIRES: asserts
+
+; CHECK-NOT: ... Skipping function with nooutline attribute: outlinable
+; CHECK-NOT: @outlined_ir_func
+; CHECK: ... Skipping function with nooutline attribute: nooutline1
+; CHECK: ... Skipping function with nooutline attribute: nooutline2
+
+define void @outlinable() { ret void }
+
+define i8 @nooutline1(ptr noalias %s, ptr noalias %d, i64 %len) "nooutline" {
+  %a = load i8, ptr %s
+  %b = load i8, ptr %d
+  call void @llvm.memcpy.p0i8.p0i8.i64(ptr %d, ptr %s, i64 %len, i1 false)
+  %c = add i8 %a, %b
+  %ret = load i8, ptr %s
+  ret i8 %ret
+}
+
+define i8 @nooutline2(ptr noalias %s, ptr noalias %d, i64 %len) "nooutline" {
+  %a = load i8, ptr %s
+  %b = load i8, ptr %d
+  call void @llvm.memcpy.p0i8.p0i8.i64(ptr %d, ptr %s, i64 %len, i1 false)
+  %c = add i8 %a, %b
+  %ret = load i8, ptr %s
+  ret i8 %ret
+}
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(ptr nocapture writeonly, ptr nocapture readonly, i64, i1)
+