--- a/build/moz.configure/rust.configure
+++ b/build/moz.configure/rust.configure
@@ -249,16 +249,18 @@ def rust_target_env_name(triple):
 # We need this to form various Cargo environment variables, as there is no
 # uppercase function in make, and we don't want to shell out just for
 # converting a string to uppercase.
 set_config('RUST_TARGET_ENV_NAME', rust_target_env_name)
 
 # This is used for putting source info into symbol files.
 set_config('RUSTC_COMMIT', depends(rustc_info)(lambda i: i.commit))
 
+set_config('RUSTC_VERSION', depends(rustc_info)(lambda i: str(i.version)))
+
 # Until we remove all the other Rust checks in old-configure.
 add_old_configure_assignment('RUSTC', rustc)
 add_old_configure_assignment('RUST_TARGET', rust_target_triple)
 
 # This option is separate from --enable-tests because Rust tests are particularly
 # expensive in terms of compile time (especially for code in libxul).
 option('--enable-rust-tests',
        help='Enable building of Rust tests, and build-time execution of them')

--- a/toolkit/library/gtest/rust/Cargo.toml
+++ b/toolkit/library/gtest/rust/Cargo.toml
@@ -9,16 +9,17 @@ description = "Testing code for libgkrus
 bindgen = ["gkrust-shared/bindgen"]
 servo = ["gkrust-shared/servo"]
 quantum_render = ["gkrust-shared/quantum_render"]
 cubeb-remoting = ["gkrust-shared/cubeb-remoting"]
 cubeb_pulse_rust = ["gkrust-shared/cubeb_pulse_rust"]
 gecko_debug = ["gkrust-shared/gecko_debug"]
 simd-accel = ["gkrust-shared/simd-accel"]
 no-static-ideograph-encoder-tables = ["gkrust-shared/no-static-ideograph-encoder-tables"]
+oom_with_global_alloc = ["gkrust-shared/oom_with_global_alloc"]
 
 [dependencies]
 mp4parse-gtest = { path = "../../../../dom/media/gtest" }
 nsstring-gtest = { path = "../../../../xpcom/rust/gtest/nsstring" }
 xpcom-gtest = { path = "../../../../xpcom/rust/gtest/xpcom" }
 gkrust-shared = { path = "../../rust/shared" }
 
 [lib]

--- a/toolkit/library/rust/Cargo.toml
+++ b/toolkit/library/rust/Cargo.toml
@@ -9,16 +9,17 @@ description = "Rust code for libxul"
 bindgen = ["gkrust-shared/bindgen"]
 servo = ["gkrust-shared/servo"]
 quantum_render = ["gkrust-shared/quantum_render"]
 cubeb-remoting = ["gkrust-shared/cubeb-remoting"]
 cubeb_pulse_rust = ["gkrust-shared/cubeb_pulse_rust"]
 gecko_debug = ["gkrust-shared/gecko_debug"]
 simd-accel = ["gkrust-shared/simd-accel"]
 no-static-ideograph-encoder-tables = ["gkrust-shared/no-static-ideograph-encoder-tables"]
+oom_with_global_alloc = ["gkrust-shared/oom_with_global_alloc"]
 
 [dependencies]
 gkrust-shared = { path = "shared" }
 
 [dev-dependencies]
 stylo_tests = { path = "../../../servo/ports/geckolib/tests/" }
 
 [lib]

--- a/toolkit/library/rust/gkrust-features.mozbuild
+++ b/toolkit/library/rust/gkrust-features.mozbuild
@@ -19,8 +19,13 @@ if CONFIG['MOZ_RUST_SIMD']:
     gkrust_features += ['simd-accel']
 
 # This feature is only supported on Linux and macOS, and this check needs to
 # match MOZ_CUBEB_REMOTING in CubebUtils.cpp.
 if (CONFIG['OS_ARCH'] == 'Linux' and CONFIG['OS_TARGET'] != 'Android') or CONFIG['OS_ARCH'] == 'Darwin':
     gkrust_features += ['cubeb-remoting']
 
 gkrust_features += ['no-static-ideograph-encoder-tables']
+
+# See details in toolkit/library/rust/shared/lib.rs
+# A string test is not the best thing, but it works well enough here.
+if CONFIG['RUSTC_VERSION'] < "1.27":
+    gkrust_features += ['oom_with_global_alloc']

--- a/toolkit/library/rust/shared/Cargo.toml
+++ b/toolkit/library/rust/shared/Cargo.toml
@@ -33,16 +33,17 @@ default = []
 bindgen = ["geckoservo/bindgen"]
 servo = ["geckoservo"]
 quantum_render = ["webrender_bindings"]
 cubeb-remoting = ["cubeb-sys", "audioipc-client", "audioipc-server"]
 cubeb_pulse_rust = ["cubeb-sys", "cubeb-pulse"]
 gecko_debug = ["geckoservo/gecko_debug", "nsstring/gecko_debug"]
 simd-accel = ["encoding_c/simd-accel", "encoding_glue/simd-accel"]
 no-static-ideograph-encoder-tables = ["encoding_c/no-static-ideograph-encoder-tables", "encoding_glue/no-static-ideograph-encoder-tables"]
+oom_with_global_alloc = []
 
 [lib]
 path = "lib.rs"
 test = false
 doctest = false
 bench = false
 doc = false
 plugin = false

new file mode 100644
--- /dev/null
+++ b/toolkit/library/rust/shared/build.rs
@@ -0,0 +1,8 @@
+fn main() {
+    // This is a rather awful thing to do, but we're only doing it on
+    // versions of rustc, >= 1.24 < 1.27, that are not going to change
+    // the unstable APIs we use from under us (1.26 being a beta as of
+    // writing, and close to release).
+    #[cfg(feature = "oom_with_global_alloc")]
+    println!("cargo:rustc-env=RUSTC_BOOTSTRAP=1");
+}

--- a/toolkit/library/rust/shared/lib.rs
+++ b/toolkit/library/rust/shared/lib.rs
@@ -1,12 +1,15 @@
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+#![cfg_attr(feature = "oom_with_global_alloc",
+            feature(global_allocator, alloc, alloc_system, allocator_api))]
+
 #[cfg(feature="servo")]
 extern crate geckoservo;
 
 extern crate mp4parse_capi;
 extern crate nsstring;
 extern crate nserror;
 extern crate xpcom;
 extern crate netwerk_helper;
@@ -154,8 +157,64 @@ pub extern "C" fn get_rust_panic_reason(
             *reason = s as *const c_char;
             *length = (*s).len();
             true
         } else {
             false
         }
     }
 }
+
+// Wrap the rust system allocator to override the OOM handler, redirecting
+// to Gecko's, which interacts with the crash reporter.
+// This relies on unstable APIs that have not changed between 1.24 and 1.27.
+// In 1.27, the API changed, so we'll need to adapt to those changes before
+// we can ship with 1.27. As of writing, there might still be further changes
+// to those APIs before 1.27 is released, so we wait for those.
+#[cfg(feature = "oom_with_global_alloc")]
+mod global_alloc {
+    extern crate alloc;
+    extern crate alloc_system;
+
+    use self::alloc::allocator::{Alloc, AllocErr, Layout};
+    use self::alloc_system::System;
+
+    pub struct GeckoHeap;
+
+    extern "C" {
+        fn GeckoHandleOOM(size: usize) -> !;
+    }
+
+    unsafe impl<'a> Alloc for &'a GeckoHeap {
+        unsafe fn alloc(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+            System.alloc(layout)
+        }
+
+        unsafe fn dealloc(&mut self, ptr: *mut u8, layout: Layout) {
+            System.dealloc(ptr, layout)
+        }
+
+        fn oom(&mut self, e: AllocErr) -> ! {
+            match e {
+                AllocErr::Exhausted { request } => unsafe { GeckoHandleOOM(request.size()) },
+                _ => System.oom(e),
+            }
+        }
+
+        unsafe fn realloc(
+            &mut self,
+            ptr: *mut u8,
+            layout: Layout,
+            new_layout: Layout,
+        ) -> Result<*mut u8, AllocErr> {
+            System.realloc(ptr, layout, new_layout)
+        }
+
+        unsafe fn alloc_zeroed(&mut self, layout: Layout) -> Result<*mut u8, AllocErr> {
+            System.alloc_zeroed(layout)
+        }
+    }
+
+}
+
+#[cfg(feature = "oom_with_global_alloc")]
+#[global_allocator]
+static HEAP: global_alloc::GeckoHeap = global_alloc::GeckoHeap;

--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -226,16 +226,18 @@
 #include "sandboxPermissions.h"
 #endif
 #endif
 
 #ifdef MOZ_CODE_COVERAGE
 #include "mozilla/CodeCoverageHandler.h"
 #endif
 
+#include "mozilla/mozalloc_oom.h"
+
 extern uint32_t gRestartMode;
 extern void InstallSignalHandlers(const char *ProgramName);
 
 #define FILE_COMPATIBILITY_INFO NS_LITERAL_CSTRING("compatibility.ini")
 #define FILE_INVALIDATE_CACHES NS_LITERAL_CSTRING(".purgecaches")
 #define FILE_STARTUP_INCOMPLETE NS_LITERAL_STRING(".startup-incomplete")
 
 int    gArgc;
@@ -5364,8 +5366,15 @@ OverrideDefaultLocaleIfNeeded() {
 }
 
 void
 XRE_EnableSameExecutableForContentProc() {
   if (!PR_GetEnv("MOZ_SEPARATE_CHILD_PROCESS")) {
     mozilla::ipc::GeckoChildProcessHost::EnableSameExecutableForContentProc();
   }
 }
+
+// Because rust doesn't handle weak symbols, this function wraps the weak
+// malloc_handle_oom for it.
+extern "C" void
+GeckoHandleOOM(size_t size) {
+  mozalloc_handle_oom(size);
+}