Index: include/clang/Driver/ToolChain.h
===================================================================
--- include/clang/Driver/ToolChain.h
+++ include/clang/Driver/ToolChain.h
@@ -408,9 +408,10 @@
   /// This checks for presence of the -Ofast, -ffast-math or -funsafe-math flags.
   virtual bool AddFastMathRuntimeIfAvailable(
       const llvm::opt::ArgList &Args, llvm::opt::ArgStringList &CmdArgs) const;
-  /// addProfileRTLibs - When -fprofile-instr-profile is specified, try to pass
+
+  /// addProfileRTOpts - When -fprofile-instr-profile is specified, try to pass
   /// a suitable profile runtime library to the linker.
-  virtual void addProfileRTLibs(const llvm::opt::ArgList &Args,
+  virtual void addProfileRTOpts(const llvm::opt::ArgList &Args,
                                 llvm::opt::ArgStringList &CmdArgs) const;
 
   /// \brief Add arguments to use system-specific CUDA includes.
Index: lib/Driver/ToolChain.cpp
===================================================================
--- lib/Driver/ToolChain.cpp
+++ lib/Driver/ToolChain.cpp
@@ -518,7 +518,7 @@
 
 void ToolChain::addClangWarningOptions(ArgStringList &CC1Args) const {}
 
-void ToolChain::addProfileRTLibs(const llvm::opt::ArgList &Args,
+void ToolChain::addProfileRTOpts(const llvm::opt::ArgList &Args,
                                  llvm::opt::ArgStringList &CmdArgs) const {
   if (!needsProfileRT(Args)) return;
 
Index: lib/Driver/ToolChains.h
===================================================================
--- lib/Driver/ToolChains.h
+++ lib/Driver/ToolChains.h
@@ -289,7 +289,7 @@
 
   /// Add any profiling runtime libraries that are needed. This is essentially a
   /// MachO specific version of addProfileRT in Tools.cpp.
-  void addProfileRTLibs(const llvm::opt::ArgList &Args,
+  void addProfileRTOpts(const llvm::opt::ArgList &Args,
                         llvm::opt::ArgStringList &CmdArgs) const override {
     // There aren't any profiling libs for embedded targets currently.
   }
@@ -403,7 +403,7 @@
             !isTargetWatchOS());
   }
 
-  void addProfileRTLibs(const llvm::opt::ArgList &Args,
+  void addProfileRTOpts(const llvm::opt::ArgList &Args,
                         llvm::opt::ArgStringList &CmdArgs) const override;
 
 protected:
@@ -808,7 +808,7 @@
                           llvm::opt::ArgStringList &CC1Args) const override;
   bool isPIEDefault() const override;
   SanitizerMask getSupportedSanitizers() const override;
-  void addProfileRTLibs(const llvm::opt::ArgList &Args,
+  void addProfileRTOpts(const llvm::opt::ArgList &Args,
                         llvm::opt::ArgStringList &CmdArgs) const override;
   virtual std::string computeSysRoot() const;
 
Index: lib/Driver/ToolChains.cpp
===================================================================
--- lib/Driver/ToolChains.cpp
+++ lib/Driver/ToolChains.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Process.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/TargetParser.h"
 #include "llvm/Support/raw_ostream.h"
@@ -349,13 +350,25 @@
   llvm_unreachable("Unsupported platform");
 }
 
-void Darwin::addProfileRTLibs(const ArgList &Args,
+void Darwin::addProfileRTOpts(const ArgList &Args,
                               ArgStringList &CmdArgs) const {
   if (!needsProfileRT(Args)) return;
 
   AddLinkRuntimeLib(Args, CmdArgs, (Twine("libclang_rt.profile_") +
        getOSLibraryNameSuffix() + ".a").str(),
                     /*AlwaysLink*/ true);
+
+  const char *PageSizeStr = Args.MakeArgString(
+      "0x" + llvm::utohexstr(llvm::sys::Process::getPageSize()));
+  auto AlignSection = [&](StringRef SectionName) {
+    CmdArgs.push_back("-sectalign");
+    CmdArgs.push_back("__DATA");
+    CmdArgs.push_back(SectionName.data());
+    CmdArgs.push_back(PageSizeStr);
+  };
+
+  // Try to page-align the counter section so that it can be mmap'd to disk.
+  AlignSection(llvm::getInstrProfCountersSectionName(/*AddSegment*/ false));
 }
 
 void DarwinClang::AddLinkSanitizerLibArgs(const ArgList &Args,
@@ -4158,7 +4171,7 @@
   return Res;
 }
 
-void Linux::addProfileRTLibs(const llvm::opt::ArgList &Args,
+void Linux::addProfileRTOpts(const llvm::opt::ArgList &Args,
                              llvm::opt::ArgStringList &CmdArgs) const {
   if (!needsProfileRT(Args)) return;
 
@@ -4167,7 +4180,7 @@
   if (!Args.hasArg(options::OPT_coverage))
     CmdArgs.push_back(Args.MakeArgString(
         Twine("-u", llvm::getInstrProfRuntimeHookVarName())));
-  ToolChain::addProfileRTLibs(Args, CmdArgs);
+  ToolChain::addProfileRTOpts(Args, CmdArgs);
 }
 
 /// DragonFly - DragonFly tool chain which can call as(1) and ld(1) directly.
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -7583,7 +7583,7 @@
   if (Args.hasArg(options::OPT_fnested_functions))
     CmdArgs.push_back("-allow_stack_execute");
 
-  getMachOToolChain().addProfileRTLibs(Args, CmdArgs);
+  getMachOToolChain().addProfileRTOpts(Args, CmdArgs);
 
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
     if (getToolChain().getDriver().CCCIsCXX())
@@ -7779,7 +7779,7 @@
   }
   CmdArgs.push_back(Args.MakeArgString(getToolChain().GetFilePath("crtn.o")));
 
-  getToolChain().addProfileRTLibs(Args, CmdArgs);
+  getToolChain().addProfileRTOpts(Args, CmdArgs);
 
   const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
@@ -8384,7 +8384,7 @@
     CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crtn.o")));
   }
 
-  ToolChain.addProfileRTLibs(Args, CmdArgs);
+  ToolChain.addProfileRTOpts(Args, CmdArgs);
 
   const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
@@ -8677,7 +8677,7 @@
     CmdArgs.push_back(Args.MakeArgString(getToolChain().GetFilePath("crtn.o")));
   }
 
-  getToolChain().addProfileRTLibs(Args, CmdArgs);
+  getToolChain().addProfileRTOpts(Args, CmdArgs);
 
   const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
@@ -9217,7 +9217,7 @@
   bool NeedsSanitizerDeps = addSanitizerRuntimes(ToolChain, Args, CmdArgs);
   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs);
   // The profile runtime also needs access to system libraries.
-  getToolChain().addProfileRTLibs(Args, CmdArgs);
+  getToolChain().addProfileRTOpts(Args, CmdArgs);
 
   if (D.CCCIsCXX() &&
       !Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
@@ -9526,7 +9526,7 @@
 
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs);
 
-  getToolChain().addProfileRTLibs(Args, CmdArgs);
+  getToolChain().addProfileRTOpts(Args, CmdArgs);
 
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
     if (D.CCCIsCXX()) {
@@ -9695,7 +9695,7 @@
     CmdArgs.push_back(Args.MakeArgString(getToolChain().GetFilePath("crtn.o")));
   }
 
-  getToolChain().addProfileRTLibs(Args, CmdArgs);
+  getToolChain().addProfileRTOpts(Args, CmdArgs);
 
   const char *Exec = Args.MakeArgString(getToolChain().GetLinkerPath());
   C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
@@ -9865,7 +9865,7 @@
     A.renderAsInput(Args, CmdArgs);
   }
 
-  TC.addProfileRTLibs(Args, CmdArgs);
+  TC.addProfileRTOpts(Args, CmdArgs);
 
   // We need to special case some linker paths.  In the case of lld, we need to
   // translate 'lld' into 'lld-link', and in the case of the regular msvc
Index: test/Driver/instrprof-ld.c
===================================================================
--- test/Driver/instrprof-ld.c
+++ test/Driver/instrprof-ld.c
@@ -73,6 +73,7 @@
 //
 // CHECK-DARWIN-X86-64: "{{(.*[^-.0-9A-Z_a-z])?}}ld{{(.exe)?}}"
 // CHECK-DARWIN-X86-64: "{{.*}}/Inputs/resource_dir{{/|\\\\}}lib{{/|\\\\}}darwin{{/|\\\\}}libclang_rt.profile_osx.a"
+// CHECK-DARWIN-X86-64: "-sectalign" "__DATA" "__llvm_prf_cnts" "0x{{[0-9a-f]+}}"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target x86_64-apple-darwin14 -fprofile-instr-generate -nostdlib \
@@ -81,6 +82,7 @@
 //
 // CHECK-DARWIN-NOSTDLIB-X86-64: "{{(.*[^-.0-9A-Z_a-z])?}}ld{{(.exe)?}}"
 // CHECK-DARWIN-NOSTDLIB-X86-64: "{{.*}}/Inputs/resource_dir{{/|\\\\}}lib{{/|\\\\}}darwin{{/|\\\\}}libclang_rt.profile_osx.a"
+// CHECK-DARWIN-NOSTDLIB-X86-64: "-sectalign" "__DATA" "__llvm_prf_cnts" "0x{{[0-9a-f]+}}"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target arm64-apple-ios -fprofile-instr-generate \
@@ -89,6 +91,7 @@
 //
 // CHECK-DARWIN-ARM64: "{{(.*[^-.0-9A-Z_a-z])?}}ld{{(.exe)?}}"
 // CHECK-DARWIN-ARM64: "{{.*}}/Inputs/resource_dir{{/|\\\\}}lib{{/|\\\\}}darwin{{/|\\\\}}libclang_rt.profile_ios.a"
+// CHECK-DARWIN-ARM64-X86-64: "-sectalign" "__DATA" "__llvm_prf_cnts" "0x{{[0-9a-f]+}}"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target armv7-apple-darwin -mtvos-version-min=8.3 -fprofile-instr-generate \
@@ -97,6 +100,7 @@
 //
 // CHECK-TVOS-ARMV7: "{{(.*[^-.0-9A-Z_a-z])?}}ld{{(.exe)?}}"
 // CHECK-TVOS-ARMV7: "{{.*}}/Inputs/resource_dir{{/|\\\\}}lib{{/|\\\\}}darwin{{/|\\\\}}libclang_rt.profile_tvos.a"
+// CHECK-TVOS-ARMV7: "-sectalign" "__DATA" "__llvm_prf_cnts" "0x{{[0-9a-f]+}}"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target armv7s-apple-darwin10 -mwatchos-version-min=2.0 -arch armv7k -fprofile-instr-generate \
@@ -105,6 +109,7 @@
 //
 // CHECK-WATCHOS-ARMV7: "{{(.*[^-.0-9A-Z_a-z])?}}ld{{(.exe)?}}"
 // CHECK-WATCHOS-ARMV7: "{{.*}}/Inputs/resource_dir{{/|\\\\}}lib{{/|\\\\}}darwin{{/|\\\\}}libclang_rt.profile_watchos.a"
+// CHECK-WATCHOS-ARMV7: "-sectalign" "__DATA" "__llvm_prf_cnts" "0x{{[0-9a-f]+}}"
 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -target i386-pc-win32 -fprofile-instr-generate \