Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -425,6 +425,12 @@
 set(LLVM_USE_SANITIZER "" CACHE STRING
   "Define the sanitizer used to build binaries and tests.")
 
+option(LLVM_SANITIZERS_TO_USE_SOFTWARE_MEMORY_MANAGER
+  "Experimental: Do not rely on availability of mmap() in sanitizers." OFF)
+if(LLVM_SANITIZERS_TO_USE_SOFTWARE_MEMORY_MANAGER)
+  add_definitions(-DLLVM_SANITIZERS_TO_USE_SOFTWARE_MEMORY_MANAGER)
+endif()
+
 option(LLVM_USE_SPLIT_DWARF
   "Use -gsplit-dwarf when compiling llvm." OFF)
 
Index: lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -137,6 +137,14 @@
 
 static const unsigned kAllocaRzSize = 32;
 
+// With the software memory manager enabled we need the RTL to handle all
+// shadow memory accesses.
+#ifdef LLVM_SANITIZERS_TO_USE_SOFTWARE_MEMORY_MANAGER
+static const bool kUseSoftwareMemoryManager = true;
+#else
+static const bool kUseSoftwareMemoryManager = false;
+#endif
+
 // Command-line flags.
 static cl::opt<bool> ClEnableKasan(
     "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
@@ -2210,7 +2218,7 @@
   }
 
   bool UseCalls =
-      CompileKernel ||
+      CompileKernel || kUseSoftwareMemoryManager ||
       (ClInstrumentationWithCallsThreshold >= 0 &&
        ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
   const DataLayout &DL = F.getParent()->getDataLayout();