Index: lib/Transforms/IPO/ArgumentPromotion.cpp
===================================================================
--- lib/Transforms/IPO/ArgumentPromotion.cpp
+++ lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -817,6 +817,12 @@
                  unsigned MaxElements,
                  Optional<function_ref<void(CallSite OldCS, CallSite NewCS)>>
                      ReplaceCallSite) {
+  // Don't perform argument promotion for naked functions; otherwise we can end
+  // up removing parameters that are seemingly 'not used' as they are referred
+  // to in the assembly.
+  if(F->hasFnAttribute(Attribute::Naked))
+    return nullptr;
+
   // Make sure that it is local to this module.
   if (!F->hasLocalLinkage())
     return nullptr;
Index: lib/Transforms/IPO/FunctionAttrs.cpp
===================================================================
--- lib/Transforms/IPO/FunctionAttrs.cpp
+++ lib/Transforms/IPO/FunctionAttrs.cpp
@@ -1136,7 +1136,8 @@
   bool HasUnknownCall = false;
   for (LazyCallGraph::Node &N : C) {
     Function &F = N.getFunction();
-    if (F.hasFnAttribute(Attribute::OptimizeNone)) {
+    if (F.hasFnAttribute(Attribute::OptimizeNone) ||
+        F.hasFnAttribute(Attribute::Naked)) {
       // Treat any function we're trying not to optimize as if it were an
       // indirect call and omit it from the node set used below.
       HasUnknownCall = true;
@@ -1221,7 +1222,8 @@
   bool ExternalNode = false;
   for (CallGraphNode *I : SCC) {
     Function *F = I->getFunction();
-    if (!F || F->hasFnAttribute(Attribute::OptimizeNone)) {
+    if (!F || F->hasFnAttribute(Attribute::OptimizeNone) ||
+        F->hasFnAttribute(Attribute::Naked)) {
       // External node or function we're trying not to optimize - we both avoid
       // transform them and avoid leveraging information they provide.
       ExternalNode = true;
Index: lib/Transforms/IPO/GlobalOpt.cpp
===================================================================
--- lib/Transforms/IPO/GlobalOpt.cpp
+++ lib/Transforms/IPO/GlobalOpt.cpp
@@ -2221,6 +2221,11 @@
   for (Module::iterator FI = M.begin(), E = M.end(); FI != E; ) {
     Function *F = &*FI++;
 
+    // Don't perform global opt pass on naked functions; we don't want fast
+    // calling conventions for naked functions.
+    if (F->hasFnAttribute(Attribute::Naked))
+      continue;
+
     // Functions without names cannot be referenced outside this module.
     if (!F->hasName() && !F->isDeclaration() && !F->hasLocalLinkage())
       F->setLinkage(GlobalValue::InternalLinkage);
Index: test/Transforms/ArgumentPromotion/naked_functions.ll
===================================================================
--- /dev/null
+++ test/Transforms/ArgumentPromotion/naked_functions.ll
@@ -0,0 +1,23 @@
+; RUN: opt < %s -argpromotion -S | FileCheck %s
+
+; Don't promote paramaters of/arguments to naked functions
+
+@g = common global i32 0, align 4
+
+define i32 @bar() {
+entry:
+  %call = call i32 @foo(i32* @g)
+; CHECK: %call = call i32 @foo(i32* @g)
+  ret i32 %call
+}
+
+define internal i32 @foo(i32*) #0 {
+entry:
+  %retval = alloca i32, align 4
+  call void asm sideeffect "ldr r0, [r0] \0Abx lr        \0A", ""()
+  unreachable
+}
+
+; CHECK: define internal i32 @foo(i32*)
+
+attributes #0 = { naked }
Index: test/Transforms/FunctionAttrs/naked_functions.ll
===================================================================
--- /dev/null
+++ test/Transforms/FunctionAttrs/naked_functions.ll
@@ -0,0 +1,25 @@
+; RUN: opt -S -functionattrs %s | FileCheck %s
+; RUN: opt -S -passes='function-attrs' %s | FileCheck %s
+
+; Don't change the attributes of parameters of naked functions, in particular
+; don't mark them as readnone
+
+@g = common global i32 0, align 4
+
+define i32 @bar() {
+entry:
+  %call = call i32 @foo(i32* @g)
+; CHECK: %call = call i32 @foo(i32* @g)
+  ret i32 %call
+}
+
+define internal i32 @foo(i32*) #0 {
+entry:
+  %retval = alloca i32, align 4
+  call void asm sideeffect "ldr r0, [r0] \0Abx lr        \0A", ""()
+  unreachable
+}
+
+; CHECK: define internal i32 @foo(i32*)
+
+attributes #0 = { naked }
Index: test/Transforms/GlobalOpt/naked_functions.ll
===================================================================
--- /dev/null
+++ test/Transforms/GlobalOpt/naked_functions.ll
@@ -0,0 +1,23 @@
+; RUN: opt < %s -globalopt -S | FileCheck %s
+
+; Check that naked functions don't get marked with fast calling conventions
+
+@g = common global i32 0, align 4
+
+define i32 @bar() {
+entry:
+  %call = call i32 @foo(i32* @g)
+; CHECK: %call = call i32 @foo(i32* @g)
+  ret i32 %call
+}
+
+define internal i32 @foo(i32*) #0 {
+entry:
+  %retval = alloca i32, align 4
+  call void asm sideeffect "ldr r0, [r0] \0Abx lr        \0A", ""()
+  unreachable
+}
+
+; CHECK: define internal i32 @foo(i32*)
+
+attributes #0 = { naked }