diff --git a/examples/aobench/ao.cpp b/examples/aobench/ao.cpp
index 48cfca42..25ad30e4 100644
--- a/examples/aobench/ao.cpp
+++ b/examples/aobench/ao.cpp
@@ -55,6 +55,7 @@
 using namespace ispc;
 
 #include "../timing.h"
+#include "../cpuid.h"
 
 #define NSUBSAMPLES        2
 
@@ -103,6 +104,38 @@ savePPM(const char *fname, int w, int h)
 }
 
 
+// Make sure that the vector ISA used during compilation is supported by
+// the processor.  The ISPC_TARGET_* macro is set in the ispc-generated
+// header file that we include above.
+static void
+ensureTargetISAIsSupported() {
+#if defined(ISPC_TARGET_SSE2)
+    bool isaSupported = CPUSupportsSSE2();
+    const char *target = "SSE2";
+#elif defined(ISPC_TARGET_SSE4)
+    bool isaSupported = CPUSupportsSSE4();
+    const char *target = "SSE4";
+#elif defined(ISPC_TARGET_AVX)
+    bool isaSupported = CPUSupportsAVX();
+    const char *target = "AVX";
+#else
+#error "Unknown ISPC_TARGET_* value"
+#endif
+    if (!isaSupported) {
+        fprintf(stderr, "***\n*** Error: the ispc-compiled code uses the %s instruction "
+                "set, which isn't\n***        supported by this computer's CPU!\n", target);
+        fprintf(stderr, "***\n***        Please modify the "
+#ifdef _MSC_VER
+                "MSVC project file "
+#else
+                "Makefile "
+#endif
+                "to select another target (e.g. sse2)\n***\n");
+        exit(1);
+    }
+}
+
+
 int main(int argc, char **argv)
 {
     if (argc != 4) {
@@ -117,6 +150,8 @@ int main(int argc, char **argv)
         height = atoi (argv[3]);
     }
 
+    ensureTargetISAIsSupported();
+
     // Allocate space for output images
     img = new unsigned char[width * height * 3];
     fimg = new float[width * height * 3];
diff --git a/examples/aobench_instrumented/ao.cpp b/examples/aobench_instrumented/ao.cpp
index 5037bdc4..addd947e 100644
--- a/examples/aobench_instrumented/ao.cpp
+++ b/examples/aobench_instrumented/ao.cpp
@@ -56,6 +56,7 @@ using namespace ispc;
 
 #include "instrument.h"
 #include "../timing.h"
+#include "../cpuid.h"
 
 #define NSUBSAMPLES        2
 
@@ -102,6 +103,38 @@ savePPM(const char *fname, int w, int h)
 }
 
 
+// Make sure that the vector ISA used during compilation is supported by
+// the processor.  The ISPC_TARGET_* macro is set in the ispc-generated
+// header file that we include above.
+static void
+ensureTargetISAIsSupported() {
+#if defined(ISPC_TARGET_SSE2)
+    bool isaSupported = CPUSupportsSSE2();
+    const char *target = "SSE2";
+#elif defined(ISPC_TARGET_SSE4)
+    bool isaSupported = CPUSupportsSSE4();
+    const char *target = "SSE4";
+#elif defined(ISPC_TARGET_AVX)
+    bool isaSupported = CPUSupportsAVX();
+    const char *target = "AVX";
+#else
+#error "Unknown ISPC_TARGET_* value"
+#endif
+    if (!isaSupported) {
+        fprintf(stderr, "***\n*** Error: the ispc-compiled code uses the %s instruction "
+                "set, which isn't\n***        supported by this computer's CPU!\n", target);
+        fprintf(stderr, "***\n***        Please modify the "
+#ifdef _MSC_VER
+                "MSVC project file "
+#else
+                "Makefile "
+#endif
+                "to select another target (e.g. sse2)\n***\n");
+        exit(1);
+    }
+}
+
+
 int main(int argc, char **argv)
 {
     if (argc != 4) {
@@ -116,6 +149,8 @@ int main(int argc, char **argv)
         height = atoi (argv[3]);
     }
 
+    ensureTargetISAIsSupported();
+
     // Allocate space for output images
     img = new unsigned char[width * height * 3];
     fimg = new float[width * height * 3];
diff --git a/examples/cpuid.h b/examples/cpuid.h
new file mode 100644
index 00000000..f7ab70a8
--- /dev/null
+++ b/examples/cpuid.h
@@ -0,0 +1,66 @@
+/*
+  Copyright (c) 2010-2011, Intel Corporation
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are
+  met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+
+    * Neither the name of Intel Corporation nor the names of its
+      contributors may be used to endorse or promote products derived from
+      this software without specific prior written permission.
+
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  
+*/
+
+#ifndef ISPC_CPUID_H
+#define ISPC_CPUID_H 1
+
+#ifdef _MSC_VER
+// Provides a __cpuid() function with same signature as below
+#include <intrin.h>
+#else
+static void __cpuid(int info[4], int infoType) {
+    __asm__ __volatile__ ("cpuid"
+                          : "=a" (info[0]), "=b" (info[1]), "=c" (info[2]), "=d" (info[3])
+                          : "0" (infoType));
+}
+#endif
+
+inline bool CPUSupportsSSE2() {
+    int info[4];
+    __cpuid(info, 1);
+    return (info[3] & (1 << 26));
+}
+
+inline bool CPUSupportsSSE4() {
+    int info[4];
+    __cpuid(info, 1);
+    return (info[2] & (1 << 19));
+}
+
+inline bool CPUSupportsAVX() {
+    int info[4];
+    __cpuid(info, 1);
+    return (info[2] & (1 << 28));
+}
+
+#endif // ISPC_CPUID_H
diff --git a/examples/mandelbrot/mandelbrot.cpp b/examples/mandelbrot/mandelbrot.cpp
index 2105a335..eb32f77e 100644
--- a/examples/mandelbrot/mandelbrot.cpp
+++ b/examples/mandelbrot/mandelbrot.cpp
@@ -41,6 +41,7 @@
 #include <stdio.h>
 #include <algorithm>
 #include "../timing.h"
+#include "../cpuid.h"
 #include "mandelbrot_ispc.h"
 using namespace ispc;
 
@@ -66,6 +67,38 @@ writePPM(int *buf, int width, int height, const char *fn) {
 }
 
 
+// Make sure that the vector ISA used during compilation is supported by
+// the processor.  The ISPC_TARGET_* macro is set in the ispc-generated
+// header file that we include above.
+static void
+ensureTargetISAIsSupported() {
+#if defined(ISPC_TARGET_SSE2)
+    bool isaSupported = CPUSupportsSSE2();
+    const char *target = "SSE2";
+#elif defined(ISPC_TARGET_SSE4)
+    bool isaSupported = CPUSupportsSSE4();
+    const char *target = "SSE4";
+#elif defined(ISPC_TARGET_AVX)
+    bool isaSupported = CPUSupportsAVX();
+    const char *target = "AVX";
+#else
+#error "Unknown ISPC_TARGET_* value"
+#endif
+    if (!isaSupported) {
+        fprintf(stderr, "***\n*** Error: the ispc-compiled code uses the %s instruction "
+                "set, which isn't\n***        supported by this computer's CPU!\n", target);
+        fprintf(stderr, "***\n***        Please modify the "
+#ifdef _MSC_VER
+                "MSVC project file "
+#else
+                "Makefile "
+#endif
+                "to select another target (e.g. sse2)\n***\n");
+        exit(1);
+    }
+}
+
+
 int main() {
     unsigned int width = 768;
     unsigned int height = 512;
@@ -77,6 +110,8 @@ int main() {
     int maxIterations = 256;
     int *buf = new int[width*height];
 
+    ensureTargetISAIsSupported();
+
     //
     // Compute the image using the ispc implementation; report the minimum
     // time of three runs.
diff --git a/examples/mandelbrot_tasks/mandelbrot.cpp b/examples/mandelbrot_tasks/mandelbrot.cpp
index 50ad4cf8..44b57b76 100644
--- a/examples/mandelbrot_tasks/mandelbrot.cpp
+++ b/examples/mandelbrot_tasks/mandelbrot.cpp
@@ -41,6 +41,7 @@
 #include <stdio.h>
 #include <algorithm>
 #include "../timing.h"
+#include "../cpuid.h"
 #include "mandelbrot_ispc.h"
 using namespace ispc;
 
@@ -66,6 +67,38 @@ writePPM(int *buf, int width, int height, const char *fn) {
 }
 
 
+// Make sure that the vector ISA used during compilation is supported by
+// the processor.  The ISPC_TARGET_* macro is set in the ispc-generated
+// header file that we include above.
+static void
+ensureTargetISAIsSupported() {
+#if defined(ISPC_TARGET_SSE2)
+    bool isaSupported = CPUSupportsSSE2();
+    const char *target = "SSE2";
+#elif defined(ISPC_TARGET_SSE4)
+    bool isaSupported = CPUSupportsSSE4();
+    const char *target = "SSE4";
+#elif defined(ISPC_TARGET_AVX)
+    bool isaSupported = CPUSupportsAVX();
+    const char *target = "AVX";
+#else
+#error "Unknown ISPC_TARGET_* value"
+#endif
+    if (!isaSupported) {
+        fprintf(stderr, "***\n*** Error: the ispc-compiled code uses the %s instruction "
+                "set, which isn't\n***        supported by this computer's CPU!\n", target);
+        fprintf(stderr, "***\n***        Please modify the "
+#ifdef _MSC_VER
+                "MSVC project file "
+#else
+                "Makefile "
+#endif
+                "to select another target (e.g. sse2)\n***\n");
+        exit(1);
+    }
+}
+
+
 int main() {
     unsigned int width = 1536;
     unsigned int height = 1024;
@@ -74,6 +107,8 @@ int main() {
     float y0 = -1;
     float y1 = 1;
 
+    ensureTargetISAIsSupported();
+
     extern void TasksInit();
     TasksInit();
 
diff --git a/examples/options/options.cpp b/examples/options/options.cpp
index 5fe48f86..1f58e8eb 100644
--- a/examples/options/options.cpp
+++ b/examples/options/options.cpp
@@ -41,6 +41,7 @@ using std::max;
 
 #include "options_defs.h"
 #include "../timing.h"
+#include "../cpuid.h"
 
 #include "options_ispc.h"
 using namespace ispc;
@@ -53,7 +54,41 @@ extern void binomial_put_serial(float Sa[], float Xa[], float Ta[],
                                 float ra[], float va[], 
                                 float result[], int count);
 
+// Make sure that the vector ISA used during compilation is supported by
+// the processor.  The ISPC_TARGET_* macro is set in the ispc-generated
+// header file that we include above.
+static void
+ensureTargetISAIsSupported() {
+#if defined(ISPC_TARGET_SSE2)
+    bool isaSupported = CPUSupportsSSE2();
+    const char *target = "SSE2";
+#elif defined(ISPC_TARGET_SSE4)
+    bool isaSupported = CPUSupportsSSE4();
+    const char *target = "SSE4";
+#elif defined(ISPC_TARGET_AVX)
+    bool isaSupported = CPUSupportsAVX();
+    const char *target = "AVX";
+#else
+#error "Unknown ISPC_TARGET_* value"
+#endif
+    if (!isaSupported) {
+        fprintf(stderr, "***\n*** Error: the ispc-compiled code uses the %s instruction "
+                "set, which isn't\n***        supported by this computer's CPU!\n", target);
+        fprintf(stderr, "***\n***        Please modify the "
+#ifdef _MSC_VER
+                "MSVC project file "
+#else
+                "Makefile "
+#endif
+                "to select another target (e.g. sse2)\n***\n");
+        exit(1);
+    }
+}
+
+
 int main() {
+    ensureTargetISAIsSupported();
+    
     float *S = new float[N_OPTIONS];
     float *X = new float[N_OPTIONS];
     float *T = new float[N_OPTIONS];
diff --git a/examples/rt/rt.cpp b/examples/rt/rt.cpp
index d7a19285..fc798bfb 100644
--- a/examples/rt/rt.cpp
+++ b/examples/rt/rt.cpp
@@ -44,6 +44,7 @@
 #include <assert.h>
 #include <sys/types.h>
 #include "../timing.h"
+#include "../cpuid.h"
 #include "rt_ispc.h"
 
 using namespace ispc;
@@ -92,12 +93,46 @@ static void writeImage(int *idImage, float *depthImage, int width, int height,
 }
 
 
+// Make sure that the vector ISA used during compilation is supported by
+// the processor.  The ISPC_TARGET_* macro is set in the ispc-generated
+// header file that we include above.
+static void
+ensureTargetISAIsSupported() {
+#if defined(ISPC_TARGET_SSE2)
+    bool isaSupported = CPUSupportsSSE2();
+    const char *target = "SSE2";
+#elif defined(ISPC_TARGET_SSE4)
+    bool isaSupported = CPUSupportsSSE4();
+    const char *target = "SSE4";
+#elif defined(ISPC_TARGET_AVX)
+    bool isaSupported = CPUSupportsAVX();
+    const char *target = "AVX";
+#else
+#error "Unknown ISPC_TARGET_* value"
+#endif
+    if (!isaSupported) {
+        fprintf(stderr, "***\n*** Error: the ispc-compiled code uses the %s instruction "
+                "set, which isn't\n***        supported by this computer's CPU!\n", target);
+        fprintf(stderr, "***\n***        Please modify the "
+#ifdef _MSC_VER
+                "MSVC project file "
+#else
+                "Makefile "
+#endif
+                "to select another target (e.g. sse2)\n***\n");
+        exit(1);
+    }
+}
+
+
 int main(int argc, char *argv[]) {
     if (argc != 2) {
         fprintf(stderr, "usage: rt <filename base>\n");
         exit(1);
     }
 
+    ensureTargetISAIsSupported();
+
 #define READ(var, n)                                            \
     if (fread(&(var), sizeof(var), n, f) != (unsigned int)n) {  \
         fprintf(stderr, "Unexpected EOF reading scene file\n"); \
diff --git a/examples/simple/simple.cpp b/examples/simple/simple.cpp
index 9542532f..4a760341 100644
--- a/examples/simple/simple.cpp
+++ b/examples/simple/simple.cpp
@@ -32,12 +32,48 @@
 */
 
 #include <stdio.h>
+#include <stdlib.h>
+#include "../cpuid.h"
 
 // Include the header file that the ispc compiler generates
 #include "simple_ispc.h"
 using namespace ispc;
 
+// Make sure that the vector ISA used during compilation is supported by
+// the processor.  The ISPC_TARGET_* macro is set in the ispc-generated
+// header file that we include above.
+static void
+ensureTargetISAIsSupported() {
+#if defined(ISPC_TARGET_SSE2)
+    bool isaSupported = CPUSupportsSSE2();
+    const char *target = "SSE2";
+#elif defined(ISPC_TARGET_SSE4)
+    bool isaSupported = CPUSupportsSSE4();
+    const char *target = "SSE4";
+#elif defined(ISPC_TARGET_AVX)
+    bool isaSupported = CPUSupportsAVX();
+    const char *target = "AVX";
+#else
+#error "Unknown ISPC_TARGET_* value"
+#endif
+    if (!isaSupported) {
+        fprintf(stderr, "***\n*** Error: the ispc-compiled code uses the %s instruction "
+                "set, which isn't\n***        supported by this computer's CPU!\n", target);
+        fprintf(stderr, "***\n***        Please modify the "
+#ifdef _MSC_VER
+                "MSVC project file "
+#else
+                "Makefile "
+#endif
+                "to select another target (e.g. sse2)\n***\n");
+        exit(1);
+    }
+}
+
+
 int main() {
+    ensureTargetISAIsSupported();
+
     float vin[16], vout[16];
 
     // Initialize input buffer
diff --git a/module.cpp b/module.cpp
index b09429d8..9daf77cd 100644
--- a/module.cpp
+++ b/module.cpp
@@ -1316,6 +1316,21 @@ Module::writeHeader(const char *fn) {
     fprintf(f, "#ifndef %s\n#define %s\n\n", guard.c_str(), guard.c_str());
 
     fprintf(f, "#include <stdint.h>\n\n");
+
+    switch (g->target.isa) {
+    case Target::SSE2:
+        fprintf(f, "#define ISPC_TARGET_SSE2\n\n");
+        break;
+    case Target::SSE4:
+        fprintf(f, "#define ISPC_TARGET_SSE4\n\n");
+        break;
+    case Target::AVX:
+        fprintf(f, "#define ISPC_TARGET_AVX\n\n");
+        break;
+    default:
+        FATAL("Unhandled target in header emission");
+    }
+
     fprintf(f, "#ifdef __cplusplus\nnamespace ispc {\n#endif // __cplusplus\n\n");
 
     if (g->emitInstrumentation) {