Index: lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -460,7 +460,7 @@
 
   // Check if we have dynamic alloca.
   bool isDynamicAlloca(AllocaInst &AI) const {
-    return AI.isArrayAllocation() || !AI.isStaticAlloca();
+    return !AI.isStaticAlloca();
   }
 
   /// If it is an interesting memory access, return the PointerOperand
Index: projects/compiler-rt/test/asan/TestCases/alloca_constant_size.cc
===================================================================
--- projects/compiler-rt/test/asan/TestCases/alloca_constant_size.cc
+++ projects/compiler-rt/test/asan/TestCases/alloca_constant_size.cc
@@ -0,0 +1,29 @@
+// Regression test for https://github.com/google/sanitizers/issues/691
+
+// RUN: %clangxx_asan -O0 %s -o %t
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <alloca.h>
+#include <stdio.h>
+#include <string.h>
+
+void f1() {
+  char *dynamic_buffer = (char *)alloca(200);
+  fprintf(stderr, "dynamic_buffer = %p\n", dynamic_buffer);
+  return;
+}
+
+void f2() {
+  char buf[1024];
+  memset(buf, 'x', 1024);
+}
+
+int main(int argc, const char *argv[]) {
+  f1();
+  f2();
+  fprintf(stderr, "Done.\n");
+  return 0;
+}
+
+// CHECK-NOT: ERROR: AddressSanitizer
+// CHECK: Done.
Index: projects/compiler-rt/test/asan/TestCases/alloca_constant_size2.cc
===================================================================
--- projects/compiler-rt/test/asan/TestCases/alloca_constant_size2.cc
+++ projects/compiler-rt/test/asan/TestCases/alloca_constant_size2.cc
@@ -0,0 +1,31 @@
+// Regression test for https://github.com/google/sanitizers/issues/691
+
+// RUN: %clangxx_asan -O0 %s -o %t
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <alloca.h>
+#include <stdio.h>
+#include <string.h>
+
+static const int kDynamicArraySize = 200;
+
+void f1() {
+  char dynamic_buffer[kDynamicArraySize];
+  fprintf(stderr, "dynamic_buffer = %p\n", dynamic_buffer);
+  return;
+}
+
+void f2() {
+  char buf[1024];
+  memset(buf, 'x', 1024);
+}
+
+int main(int argc, const char *argv[]) {
+  f1();
+  f2();
+  fprintf(stderr, "Done.\n");
+  return 0;
+}
+
+// CHECK-NOT: ERROR: AddressSanitizer
+// CHECK: Done.