diff --git a/clang/test/CodeGen/asan-use-callbacks.cpp b/clang/test/CodeGen/asan-use-callbacks.cpp
--- a/clang/test/CodeGen/asan-use-callbacks.cpp
+++ b/clang/test/CodeGen/asan-use-callbacks.cpp
@@ -1,12 +1,18 @@
-// RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -fsanitize=address \
-// RUN:     -o - %s \
+// RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -o - \
+// RUN:     -fsanitize=address %s \
 // RUN:     | FileCheck %s --check-prefixes=CHECK-NO-OUTLINE
 // RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -o - \
 // RUN:     -fsanitize=address %s -fsanitize-address-outline-instrumentation \
 // RUN:     | FileCheck %s --check-prefixes=CHECK-OUTLINE
+// RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -o - \
+// RUN:     -fsanitize=address %s -fsanitize-address-outline-instrumentation \
+// RUN:     -mllvm -asan-optimize-callbacks \
+// RUN:     | FileCheck %s --check-prefixes=CHECK-OPTIMIZED
+
 
 // CHECK-NO-OUTLINE-NOT: call{{.*}}@__asan_load4
 // CHECK-OUTLINE: call{{.*}}@__asan_load4
+// CHECK-OPTIMIZED: call{{.*}}@llvm.asan.check.memaccess(i8*{{.*}}, i64{{.*}}, i32{{.*}})
 
 int deref(int *p) {
   return *p;
diff --git a/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizer.h b/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizer.h
--- a/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizer.h
+++ b/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizer.h
@@ -147,6 +147,10 @@
     bool UseOdrIndicator = true,
     AsanDtorKind DestructorKind = AsanDtorKind::Global);
 
+// Get AddressSanitizer parameters.
+void getAddressSanitizerParams(Module &M, uint64_t *ShadowBase,
+                               int *MappingScale, bool *OrShadowOffset);
+
 } // namespace llvm
 
 #endif
diff --git a/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerCommon.h b/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerCommon.h
--- a/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerCommon.h
+++ b/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerCommon.h
@@ -87,6 +87,8 @@
   return true;
 }
 
+void getASanShadowMapping(int *Scale, uint64_t *Offset, bool *OrShadowOffset);
+
 } // namespace llvm
 
 #endif
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -348,6 +348,10 @@
 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
                            cl::Hidden, cl::init(true));
 
+static cl::opt<bool> ClOptimizeCallbacks("asan-optimize-callbacks",
+                                         cl::desc("Optimize callbacks"),
+                                         cl::Hidden, cl::init(false));
+
 static cl::opt<bool> ClOptSameTemp(
     "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
     cl::Hidden, cl::init(true));
@@ -559,6 +563,17 @@
   return Mapping;
 }
 
+void getAddressSanitizerParams(Module &M, uint64_t *ShadowBase,
+                               int *MappingScale, bool *OrShadowOffset) {
+  Triple TargetTriple = Triple(M.getTargetTriple());
+  auto Mapping =
+      getShadowMapping(TargetTriple, M.getDataLayout().getPointerSizeInBits(),
+                       ClEnableKasan.getNumOccurrences() > 0);
+  *ShadowBase = Mapping.Offset;
+  *MappingScale = Mapping.Scale;
+  *OrShadowOffset = Mapping.OrShadowOffset;
+}
+
 static uint64_t getRedzoneSizeForScale(int MappingScale) {
   // Redzone used for stack and globals is at least 32 bytes.
   // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
@@ -623,6 +638,7 @@
     C = &(M.getContext());
     LongSize = M.getDataLayout().getPointerSizeInBits();
     IntptrTy = Type::getIntNTy(*C, LongSize);
+    Int8PtrTy = Type::getInt8PtrTy(*C);
     TargetTriple = Triple(M.getTargetTriple());
 
     Mapping = getShadowMapping(TargetTriple, LongSize, this->CompileKernel);
@@ -673,6 +689,7 @@
                                  Value *SizeArgument, uint32_t Exp);
   void instrumentMemIntrinsic(MemIntrinsic *MI);
   Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
+  void encodeMemToShadowInfo(int64_t *AccessInfo);
   bool suppressInstrumentationSiteForDebug(int &Instrumented);
   bool instrumentFunction(Function &F, const TargetLibraryInfo *TLI);
   bool maybeInsertAsanInitAtFunctionEntry(Function &F);
@@ -713,6 +730,7 @@
   bool UseAfterScope;
   AsanDetectStackUseAfterReturnMode UseAfterReturn;
   Type *IntptrTy;
+  Type *Int8PtrTy;
   ShadowMapping Mapping;
   FunctionCallee AsanHandleNoReturnFunc;
   FunctionCallee AsanPtrCmpFunction, AsanPtrSubFunction;
@@ -1742,12 +1760,21 @@
   size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
 
   if (UseCalls) {
-    if (Exp == 0)
-      IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
-                     AddrLong);
-    else
-      IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
-                     {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
+    if (ClOptimizeCallbacks) {
+      Value *Ptr8 = IRB.CreatePointerCast(Addr, Int8PtrTy);
+      Module *M = IRB.GetInsertBlock()->getParent()->getParent();
+      IRB.CreateCall(
+          Intrinsic::getDeclaration(M, Intrinsic::asan_check_memaccess),
+          {Ptr8, ConstantInt::get(IRB.getInt8Ty(), IsWrite),
+           ConstantInt::get(IRB.getInt8Ty(), AccessSizeIndex)});
+    } else {
+      if (Exp == 0)
+        IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
+                       AddrLong);
+      else
+        IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
+                       {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
+    }
     return;
   }