diff --git a/app/src/processing/app/debug/Compiler.java b/app/src/processing/app/debug/Compiler.java
index a3f8940a7..92f25a1c5 100644
--- a/app/src/processing/app/debug/Compiler.java
+++ b/app/src/processing/app/debug/Compiler.java
@@ -197,8 +197,14 @@ public class Compiler implements MessageConsumer {
     targetArch = targetPlatform.getId();
     p.put("build.arch", targetArch.toUpperCase());
     
-    if (!p.containsKey("compiler.path"))
+    // Platform.txt should define its own compiler.path. For
+    // compatibility with earlier 1.5 versions, we define a (ugly,
+    // avr-specific) default for it, but this should be removed at some
+    // point.
+    if (!p.containsKey("compiler.path")) {
+      System.err.println(_("Third-party platform.txt does not define compiler.path. Please report this to the third-party hardware maintainer."));
       p.put("compiler.path", Base.getAvrBasePath());
+    }
 
     // Core folder
     TargetPlatform tp = corePlatform;
diff --git a/app/src/processing/app/debug/TargetPlatform.java b/app/src/processing/app/debug/TargetPlatform.java
index da4a1b28a..3dfb29f6e 100644
--- a/app/src/processing/app/debug/TargetPlatform.java
+++ b/app/src/processing/app/debug/TargetPlatform.java
@@ -110,6 +110,20 @@ public class TargetPlatform {
           format(_("Error loading {0}"), platformsFile.getAbsolutePath()), e);
     }
 
+    // Allow overriding values in platform.txt. This allows changing
+    // platform.txt (e.g. to use a system-wide toolchain), without
+    // having to modify platform.txt (which, when running from git,
+    // prevents files being marked as changed).
+    File localPlatformsFile = new File(folder, "platform.local.txt");
+    try {
+      if (localPlatformsFile.exists() && localPlatformsFile.canRead()) {
+        preferences.load(localPlatformsFile);
+      }
+    } catch (IOException e) {
+      throw new TargetPlatformException(
+          format(_("Error loading {0}"), localPlatformsFile.getAbsolutePath()), e);
+    }
+
     File progFile = new File(folder, "programmers.txt");
     try {
       if (progFile.exists() && progFile.canRead()) {
diff --git a/hardware/arduino/avr/platform.txt b/hardware/arduino/avr/platform.txt
index 78f530aa4..58af56b07 100644
--- a/hardware/arduino/avr/platform.txt
+++ b/hardware/arduino/avr/platform.txt
@@ -12,7 +12,7 @@ version=1.5.6
 # --------------------- 
 
 # Default "compiler.path" is correct, change only if you want to overidde the initial value
-#compiler.path={ide.path}/tools/avr/bin/..
+compiler.path={runtime.ide.path}/hardware/tools/avr/bin/
 compiler.c.cmd=avr-gcc
 compiler.c.flags=-c -g -Os -w -ffunction-sections -fdata-sections -MMD
 compiler.c.elf.flags=-Os -Wl,--gc-sections
@@ -28,32 +28,42 @@ compiler.elf2hex.flags=-O ihex -R .eeprom
 compiler.elf2hex.cmd=avr-objcopy
 compiler.ldflags=
 compiler.size.cmd=avr-size
-# this can be overriden in boards.txt
+
+# This can be overriden in boards.txt
 build.extra_flags=
 
+# These can be overridden in platform.local.txt
+compiler.c.extra_flags=
+compiler.c.elf.extra_flags=
+compiler.S.extra_flags=
+compiler.cpp.extra_flags=
+compiler.ar.extra_flags=
+compiler.objcopy.eep.extra_flags=
+compiler.elf2hex.extra_flags=
+
 # AVR compile patterns
 # --------------------
 
 ## Compile c files
-recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
+recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.c.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Compile c++ files
-recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
+recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpp.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Compile S files
-recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.S.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
+recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.S.flags} -mmcu={build.mcu} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.S.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
 
 ## Create archives
-recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} "{build.path}/{archive_file}" "{object_file}"
+recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{build.path}/{archive_file}" "{object_file}"
 
 ## Combine gc-sections, archives, and objects
-recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} -mmcu={build.mcu} -o "{build.path}/{build.project_name}.elf" {object_files} "{build.path}/{archive_file}" "-L{build.path}" -lm
+recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} -mmcu={build.mcu} {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf" {object_files} "{build.path}/{archive_file}" "-L{build.path}" -lm
 
 ## Create eeprom
-recipe.objcopy.eep.pattern="{compiler.path}{compiler.objcopy.cmd}" {compiler.objcopy.eep.flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.eep"
+recipe.objcopy.eep.pattern="{compiler.path}{compiler.objcopy.cmd}" {compiler.objcopy.eep.flags} {compiler.objcopy.eep.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.eep"
 
 ## Create hex
-recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.hex"
+recipe.objcopy.hex.pattern="{compiler.path}{compiler.elf2hex.cmd}" {compiler.elf2hex.flags} {compiler.elf2hex.extra_flags} "{build.path}/{build.project_name}.elf" "{build.path}/{build.project_name}.hex"
 
 ## Compute size
 recipe.size.pattern="{compiler.path}{compiler.size.cmd}" -A "{build.path}/{build.project_name}.elf"