Index: include/llvm/FuzzMutate/FuzzerCLI.h
===================================================================
--- include/llvm/FuzzMutate/FuzzerCLI.h
+++ include/llvm/FuzzMutate/FuzzerCLI.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_FUZZMUTATE_FUZZER_CLI_H
 #define LLVM_FUZZMUTATE_FUZZER_CLI_H
 
+#include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
 
 namespace llvm {
@@ -24,6 +25,17 @@
 /// This handles all arguments after -ignore_remaining_args=1 as cl::opts.
 void parseFuzzerCLOpts(int ArgC, char *ArgV[]);
 
+/// Handle backend options that are encoded in the executable name.
+///
+/// Parses some common backend options out of a specially crafted executable
+/// name (argv[0]). For example, a name like llvm-foo-fuzzer:aarch64-gisel might
+/// set up an AArch64 triple and the Global ISel selector. This should be called
+/// *before* parseFuzzerCLOpts if calling both.
+///
+/// This is meant to be used for environments like OSS-Fuzz that aren't capable
+/// of passing in command line arguments in the normal way.
+void handleExecNameEncodedBEOpts(StringRef ExecName);
+
 using FuzzerTestFun = int (*)(const uint8_t *Data, size_t Size);
 using FuzzerInitFun = int (*)(int *argc, char ***argv);
 
Index: lib/FuzzMutate/FuzzerCLI.cpp
===================================================================
--- lib/FuzzMutate/FuzzerCLI.cpp
+++ lib/FuzzMutate/FuzzerCLI.cpp
@@ -8,7 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/FuzzMutate/FuzzerCLI.h"
-#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Error.h"
@@ -31,6 +31,38 @@
   cl::ParseCommandLineOptions(CLArgs.size(), CLArgs.data());
 }
 
+void llvm::handleExecNameEncodedBEOpts(StringRef ExecName) {
+  std::vector<std::string> Args{ExecName};
+
+  StringRef OptString = ExecName.split(':').second;
+  if (OptString.empty())
+    return;
+
+  SmallVector<StringRef, 4> Opts;
+  OptString.split(Opts, '-');
+  for (StringRef Opt : Opts) {
+    if (Opt.equals("gisel")) {
+      Args.push_back("-global-isel");
+      // For now we default GlobalISel to -O0
+      Args.push_back("-O0");
+    } else if (Opt.startswith("O")) {
+      Args.push_back("-" + Opt.str());
+    } else if (auto Arch = Triple::getArchTypeForLLVMName(Opt)) {
+      Args.push_back("-mtriple=" + Opt.str());
+    } else {
+      errs() << ExecName << ": Unknown option: " << Opt << ".\n";
+      exit(1);
+    }
+  }
+
+  std::vector<const char *> CLArgs;
+  CLArgs.reserve(Args.size());
+  for (std::string &S : Args)
+    CLArgs.push_back(S.c_str());
+
+  cl::ParseCommandLineOptions(CLArgs.size(), CLArgs.data());
+}
+
 int llvm::runFuzzerOnInputs(int ArgC, char *ArgV[], FuzzerTestFun TestOne,
                             FuzzerInitFun Init) {
   errs() << "*** This tool was not linked to libFuzzer.\n"
Index: test/tools/llvm-isel-fuzzer/execname-options.ll
===================================================================
--- test/tools/llvm-isel-fuzzer/execname-options.ll
+++ test/tools/llvm-isel-fuzzer/execname-options.ll
@@ -0,0 +1,27 @@
+; REQUIRES: aarch64-registered-target
+
+; RUN: echo > %t.input
+
+; RUN: cp llvm-isel-fuzzer %t.bin:aarch64
+; RUN: %t.bin:aarch64 %t.input 2>&1 | FileCheck %s
+
+; RUN: mv %t.bin:aarch64 %t.bin:aarch64-O1
+; RUN: %t.bin:aarch64-O1 %t.input 2>&1 | FileCheck %s
+
+; RUN: mv %t.bin:aarch64-O1 %t.bin:O1-aarch64
+; RUN: %t.bin:O1-aarch64 %t.input 2>&1 | FileCheck %s
+
+; RUN: mv %t.bin:O1-aarch64 %t.bin:aarch64-gisel
+; RUN: %t.bin:aarch64-gisel %t.input 2>&1 | FileCheck %s
+
+; CHECK: Running
+
+; RUN: mv %t.bin:aarch64-gisel %t.bin:gisel-O0
+; RUN: not %t.bin:gisel-O0 %t.input 2>&1 | FileCheck -check-prefix=NO-TRIPLE %s
+
+; NO-TRIPLE: -mtriple must be specified
+
+; RUN: mv %t.bin:gisel-O0 %t.bin:unexist
+; RUN: not %t.bin:unexist %t.input 2>&1 | FileCheck -check-prefix=NO-OPT %s
+
+; NO-OPT: Unknown option:
Index: tools/llvm-isel-fuzzer/llvm-isel-fuzzer.cpp
===================================================================
--- tools/llvm-isel-fuzzer/llvm-isel-fuzzer.cpp
+++ tools/llvm-isel-fuzzer/llvm-isel-fuzzer.cpp
@@ -150,6 +150,7 @@
   InitializeAllAsmPrinters();
   InitializeAllAsmParsers();
 
+  handleExecNameEncodedBEOpts(*argv[0]);
   parseFuzzerCLOpts(*argc, *argv);
 
   if (TargetTriple.empty()) {