Index: include/llvm/MC/MCAsmInfo.h
===================================================================
--- include/llvm/MC/MCAsmInfo.h
+++ include/llvm/MC/MCAsmInfo.h
@@ -256,6 +256,10 @@
   /// argument and how it is interpreted.  Defaults to NoAlignment.
   LCOMM::LCOMMType LCOMMDirectiveAlignmentType;
 
+  // True if the target allows .align directives on funtions. This is true for
+  // most targets, so defaults to true.
+  bool HasFunctionAlignment;
+
   /// True if the target has .type and .size directives, this is true for most
   /// ELF targets.  Defaults to true.
   bool HasDotTypeDotSizeDirective;
@@ -467,6 +471,7 @@
   LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
     return LCOMMDirectiveAlignmentType;
   }
+  bool hasFunctionAlignment() const { return HasFunctionAlignment; }
   bool hasDotTypeDotSizeDirective() const { return HasDotTypeDotSizeDirective; }
   bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
   bool hasIdentDirective() const { return HasIdentDirective; }
Index: lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -527,7 +527,8 @@
   EmitVisibility(CurrentFnSym, F->getVisibility());
 
   EmitLinkage(F, CurrentFnSym);
-  EmitAlignment(MF->getAlignment(), F);
+  if (MAI->hasFunctionAlignment())
+    EmitAlignment(MF->getAlignment(), F);
 
   if (MAI->hasDotTypeDotSizeDirective())
     OutStreamer.EmitSymbolAttribute(CurrentFnSym, MCSA_ELF_TypeFunction);
Index: lib/MC/MCAsmInfo.cpp
===================================================================
--- lib/MC/MCAsmInfo.cpp
+++ lib/MC/MCAsmInfo.cpp
@@ -69,6 +69,7 @@
   HasAggressiveSymbolFolding = true;
   COMMDirectiveAlignmentIsInBytes = true;
   LCOMMDirectiveAlignmentType = LCOMM::NoAlignment;
+  HasFunctionAlignment = true;
   HasDotTypeDotSizeDirective = true;
   HasSingleParameterDotFile = true;
   HasIdentDirective = false;
Index: lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
===================================================================
--- lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
+++ lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
@@ -39,6 +39,8 @@
   InlineAsmEnd = " inline asm";
 
   SupportsDebugInformation = CompileForDebugging;
+  // PTX does not allow .align on functions.
+  HasFunctionAlignment = false;
   HasDotTypeDotSizeDirective = false;
 
   Data8bitsDirective = " .b8 ";
Index: test/CodeGen/NVPTX/function-align.ll
===================================================================
--- /dev/null
+++ test/CodeGen/NVPTX/function-align.ll
@@ -0,0 +1,7 @@
+; RUN: llc < %s -march=nvptx -mcpu=sm_20 | FileCheck %s
+
+; CHECK-NOT: .align 2
+define ptx_device void @foo() align 2 {
+; CHECK-LABEL: .func foo
+  ret void
+}